The ART of falling pregnant after 35 years of age

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So, why does age matter when it comes to fertility?

Put simply, as you get older, the number and quality of your eggs decrease. Unlike men, who continue to produce new sperm throughout their lives, a woman is born with all the eggs she will ever have. While sperm quality (shape and speed) falls as a man ages, there is little effect on fertility or the child until men enter their mid-50s.

Thus, if you are over 35 and haven’t fallen pregnant within six months of trying, we may begin our assessment by checking your ‘ovarian reserve’. There are two tests we commonly use.

Two common fertility tests

The first involves measuring the level of anti-mullerian hormone (AMH) in your blood. This hormone is secreted by the cells that surround and protect the eggs, so it gives us an idea of how many eggs you have left (the higher the hormone, the higher the number of eggs you are likely to have left). We can then assess if your egg reserve is about what we would expect given your age.

The second test we can use is called an ‘antral follicle count’. An ultrasound is performed (usually in the first week after a period) to look at your ovaries and count the number of follicles (small ovarian cysts containing the eggs that will grow that month).

Although both tests will help inform our approach to your fertility treatment, neither test tells us anything about the quality of your remaining eggs (only the quantity relative to your age).

Fertility treatment options for women over 35 years

While it may be hard to hear that you are statistically less likely to conceive after the age of 35 than you were in your 20s, the good news is that there are now a number of fertility treatments available to assist couples who start trying for a baby later in life but then find that they’re unable to conceive naturally.

Some of the options that may be presented to you include:

1. Ovulation tracking

­This is a relatively simple approach where we track your menstrual cycle using blood and ultrasound tests. By doing so, we can tell you when you are most fertile (i.e. most likely to release an egg from your ovary), so you can align the timing of sexual intercourse accordingly. Basically, we want egg and sperm to both be in the same place at the same time, thereby improving your chances of fertilisation (i.e. egg meeting sperm and joining to form an embryo). This is a bit like the old TV show ‘Perfect Match’, where one girl (i.e. one egg) has her choice of a few different men (i.e. the millions of sperm present in a man’s semen), but it doesn’t necessarily mean she’ll hit it off with any of them. We are more likely to try this approach first if your AMH test shows that you have a good egg reserve. Note: if you have tried an over-the-counter home ovulation kit, be aware that ovulation tracking in the clinic is more accurate.

2. Ovulation induction

If your egg reserve is good, we may use medication to encourage your ovaries to release a small army of mature eggs. Again, sex is then timed accordingly, so a team of eggs and a team of sperm are both ‘hanging out’ in your reproductive tract at the same time – the equivalent of a group date where you just have to wait and see if anyone hits it off! Occasionally, we will also use medication to ‘trigger’ the release of eggs at the optimum time.

3. Intrauterine insemination (IUI)

If we think there is an issue with sperm getting to where it needs to be in your reproductive tract (i.e. having sex at the right time is not the problem), we may suggest pre-collecting your partner’s semen, so that we can ‘flush’ a large amount of highly concentrated sperm directly into your womb (with a syringe) around the time of ovulation. We may use this approach in combination with ovulation tracking or induction to ensure an egg is also available to meet the sperm.

4. In vitro fertilisation (IVF) using your own eggs

IVF involves stimulating your ovaries to produce multiple mature eggs, collecting these eggs, and then placing them with sperm in a laboratory dish. Ideally, the sperm will then fertilise one or more of your eggs, resulting in an embryo/s. One embryo is then placed into your womb in the hope that it snugly implants in the wall of your uterus, leading to pregnancy (any other embryos remain frozen for future use). By placing egg and sperm together outside the body, we help overcome any barriers that may be preventing this process from occurring naturally. Unfortunately, the revolutionary science of IVF cannot make up for the natural decline in fertility that occurs with age, including a drop in egg quality, which means that IVF success rates do tend to drop as women get older.

5. Pre-implantation Genetic Testing (PGT) of embryos as part of the IVF process

If you are an older woman undergoing IVF, we may recommend genetically testing your embryos before placing them in your womb to help improve your chances of a successful cycle. You can read more about PGT elsewhere on our website, but essentially, these tests involve checking your embryos for genetic anomalies, so that we can select the embryo with the best potential for development for transfer into your womb. These tests can be particularly helpful for older women because the incidence of genetic abnormalities increases with age, leading to higher rates of implantation failure and miscarriage with IVF. Thus, if we can identify the highest-quality embryo for transfer, we give IVF the best chance of success.

6. In vitro fertilisation (IVF) with ICSI or IMSI

ICSI or IMSI may also be used during IVF to improve your chances of success. Again, you can read about ICSI and IMSI elsewhere on our website, but in general, these techniques help overcome any sperm-related issues that may be impacting your ability to fall pregnant naturally. While sperm ‘problems’ are not necessarily a sign of older age, certain health or lifestyle issues can be more common with age, which may impact the quality and quantity of your partner’s sperm. ICSI may also be used if there are no obvious sperm problems but fertilisation failed during one or more previous IVF cycles (i.e. when eggs and sperm were placed together in a laboratory dish, no pairs came together to form an embryo).

7. In vitro fertilisation (IVF) using donor eggs

If you’re older and do not succeed with IVF using your own eggs, egg donation from a younger woman may improve your chances of having a baby via IVF. Studies show that if an older woman undergoes IVF using eggs from a younger donor, her chances of having a baby match the donor’s age group. IVF using donor eggs is also an option for women whose ovaries don’t produce any mature eggs despite hormonal stimulation or who have entered menopause prematurely (< 40 years old).<

8. Solo parenthood with donor sperm

If you are an older, single woman without a male partner but want to try for a baby on your own, donor sperm with the help of IUI or IVF now makes this very possible. However, it’s better to make this decision earlier rather than later, while you are still likely to have a good number of quality eggs. Every year after 35 reduces your chances of having a successful pregnancy, even with the help of IUI or IVF.

Additional considerations for women over 35 years

Fertility preservation through egg freezing

For women who are not yet ready to start a family, egg freezing offers a proactive way to preserve fertility. Whether the result of personal, professional or health reasons, elective or medical egg freezing allows younger, healthier eggs to be stored for future use. At Newlife IVF, this process involves ovarian stimulation, egg collection under light sedation, and vitrification (rapid freezing) of mature eggs at our Box Hill day surgery.

Success rates depend on age and the number of eggs frozen. For instance, freezing 20 eggs at age 30 offers a 90% chance of a live birth. Comparatively, the probability of achieving a live birth reduces to 75% when 20 eggs are frozen at age 37.

We offer transparent pricing and personalised advice from our fertility specialists, helping you make informed decisions about fertility preservation in Melbourne and across Victoria.

Learn more about egg freezing at Newlife IVF.

Fertility-friendly lifestyle habits

Lifestyle factors play a key role in fertility for both men and women. Making positive changes to your health and habits can significantly increase your chances of falling pregnant after 35. At Newlife IVF, we recommend:

  • Maintaining a healthy weight: A BMI between 18.5 and 25 improves hormonal balance, ovulation and sperm quality
  • Following a Mediterranean-style diet: A balanced diet rich in vegetables, whole grains, healthy fats, and lean proteins supports egg, embryo and sperm quality
  • Limiting alcohol and caffeine: Reduce your caffeine intake to one caffeinated drink daily, and aim for at least two alcohol-free days each week
  • Quitting smoking and avoiding vaping or illicit drugs: These substances have been shown to reduce egg and sperm quality and increase miscarriage risk
  • Engaging in moderate (not excessive) exercise: Aim for 30–40 minutes of physical activity 3 times per week. Avoid exercising for more than 4 hours per week at high intensity
  • Optimising your sleep: Disrupted sleep (such as night shift work) may affect hormone levels, egg development and sperm production.

Emotional and Psychological Support

Fertility journeys can be emotionally challenging, particularly for women over 35. At Newlife IVF, we encourage the following activities to help you cope with stress and improve your day-to-day life:

  • Daily mindfulness or meditation through apps like Smiling Mind or Calm
  • Gentle activities like gardening, drawing or walking
  • Talking to a friend, counsellor or support group
  • Accessing online resources such as Mindful IVF or the IVF Warrior podcast.

Our fertility counsellors also offer ongoing support throughout your fertility journey. So if you’re feeling overwhelmed, don’t hesitate to ask our team about your fertility counselling options.

When to seek help

If you’re over 35, we advise seeking help from a fertility specialist if you don’t fall pregnant after 6 months of trying. If you’re a single woman over 35 and want to explore the option of donor sperm, we advise seeking professional help as soon as possible, as there can be a waitlist for donor sperm.

For advice specific to you, you can make an appointment with one of our fertility specialists by calling Newlife IVF on (03) 8080 8933 or by booking online via our appointments page.

Further reading

Sperm donation – separating fact from fiction

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Wanted: a few good men!

As a growing number of single women make the decision to embark on solo parenting, lesbian couples embrace techniques like artificial insemination and IVF to help them have a family, and fertility issues become more common for heterosexual couples who meet and marry later in life, there’s never been a more appropriate time for Australian men to donate their sperm.

However, despite a clear need for more donor sperm, there’s still a lot of myths around sperm donation, and understandably, men are often hesitant to put themselves forward. Here, we explore the truth behind the most common misconceptions to help overcome some of the fears men may have about becoming a donor.

“Gay men can’t donate sperm.”

A gay man can donate sperm just like any other healthy male. In Australia, sexual orientation plays no part in deciding whether or not you can become a sperm donor (admittedly, this is a clear contrast to the policies of some international sperm banks). Unfortunately, because men who have sex with men are prevented from donating blood – due to a perceived increased risk of sexually transmitted diseases – some people assume that gay men can’t donate sperm either. However, that’s simply not the case and here in Australia, gay men have actually been credited for increasing the availability of donor sperm.

The fact is, all sperm donors – no matter their sexual orientation – are screened for infectious diseases before their sperm is cleared for use. This includes blood tests at the time of donation and again at 3 months. Sperm is only made available to potential recipients after both sets of blood tests have been given the all clear (this is why donor sperm is not used straightaway but quarantined for 3 months).  Simply put, sexual orientation doesn’t form part of the eligibility criteria for sperm donors and is irrelevant to your ability to donate. Whether you’re gay, bi or straight, your intent is exactly the same – to give in order to help others in need.

“My sperm could be used to make hundreds of children.”

You may have come across news stories about men abroad who have fathered many, many children through sperm donation (some well into the double figures!). However, Australian law simply does not permit this. In Victoria, sperm from a single donor is only allowed to be used by a maximum of 10 different patients or ‘families’. This effectively limits the number of potential children that can be conceived by any one donor.

On the other hand, there is no limit to the number of children that can be born from the same sperm donor within each of these families. This gives families the opportunity to bear siblings who are genetically related. So if a recipient has success with your sperm, they may choose to use your sperm again in the future when trying for baby #2 or 3 in order to give their child a biologically-related brother or sister.

But it’s also important to realise that your sperm may never be used or may only be used once or twice. If it is used, there is also no guarantee that the process of assisted conception (e.g. IVF or IUI) will be successful for the recipient, i.e. a child may not result every time your sperm is used. Further, the semen we collect from you may also not ‘stretch’ to ten different families. This, along with unsuccessful IVF attempts, is why we like donors to provide a few sperm samples over time.

“If you donate sperm, you’ll have children showing up on your doorstep for years to come.”

The Victorian government was one of the first to query the ethical implications of the secrecy surrounding sperm donorship. As such, current legislation states that a donor-conceived person can request identifying information about their donor once they turn 18. This loss of guaranteed anonymity is one of the main reasons why the number of sperm donors has dropped over recent decades. However, although a donor-conceived child has the option of getting in touch with you once they are an adult, this doesn’t necessarily mean they will do so. Some children may not know they are donor-conceived while others will simply have no inclination to reach out.

If a child conceived from your sperm does choose to get in contact with you, you still have no legal, financial or parental responsibilities to that child. However, you may find that you are happy to build and maintain a relationship with them. In this case, you can discuss and agree together the extent of any future contact, in line with what you both feel comfortable with.

“If you’re a sperm donor, you’re a father of all the children who are born.”

When you donate your sperm, it provides the biological means to create a baby only. Men who donate sperm anonymously through a registered sperm bank are not legally or financially responsible for any child born from their sperm. Sperm donor recipients (i.e. the mum and dad to be) must also receive counselling to ensure mutual understanding of your rights as a donor. Put simply, you are just the sperm donor, not the Dad. And we make sure that everyone involved knows that they do not have the right to ask or expect you to be anything more than that.

“Only good-looking men’s sperm will be used”

Don’t think your sperm will be wanted? Think again! The reality is that recipients often have their own ideas of the ‘dream’ sperm donor. And this could be you! When it comes to donor selection, your physical attributes (e.g. blue eyes, brown hair, height) are listed but photos are never provided. More often than not, recipients will choose a donor based on other information provided, including your age, medical history, hobbies/interests, ethnic background, and reason for donating. For example, we know one woman who chose her donor based on the fact that he (like herself) had a penchant for trivia, a trait she hoped would be passed on to her future child!

The fact is, the most important attribute of any sperm bank is variety, thereby enabling choice. That’s why we welcome donors from a wide range of nationalities, cultures, professions, and stages and ages of life. This ensures that women and couples have the opportunity to choose a donor that aligns with their personal preferences, particularly if bearing a child with a clear physical resemblance or from a certain ethnic background (e.g. Asian, Anglosaxon) is important to them.

Donate life, change lives with Newlife IVF

Newlife IVF loves hearing from new sperm donors – single men, fathers, gay individuals or couples. Come one, come all! If you have been thinking about becoming a donor but haven’t yet taken the next step, please call us on (03) 8080 8933 or email [email protected] so we can give you all the facts and get your swimmers to those who need it sooner rather than later!

Further reading

Sperm donors – the hidden heros behind many of today’s families

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Sperm donors are more important than ever before

An increasing number of single women and lesbian couples are now using IVF to help them conceive. Since Victorian laws changed in 2010, allowing single women and lesbian couples to access IVF, the number of women using sperm donors has markedly increased.

These women and couples typically gain access to donor sperm by asking someone they know to donate sperm (e.g. a friend or family member) or by using an anonymous sperm donor via a registered sperm bank. Unfortunately, like blood banks, sperm banks often face shortages.

Long story short, if you’re thinking about donating your mighty fine swimmers, doing so sooner rather than later would make a world of difference to those currently waiting for donor sperm to conceive.

Need a little more motivation?

A strong desire to help others is a great start but some other reasons you may consider donating include:

You’re not ready to have children yet or don’t plan to raise a family of your own

Families are a source of joy for many of us – they can bring meaningful relationships and purpose to our lives. But if you are not yet ready to have children or not sure if you ever will, donating your sperm can help provide a similar sense of purpose and meaning. Indeed, studies have found that men who donate sperm report a sense of satisfaction that they played a role in the formation of a new life.1

You already have children, and want to help others become parents too

After experiencing the joy of parenthood yourself, you may simply want to give those who can’t conceive naturally the extra help they need to start their own family.

You’ve seen people struggle with fertility issues

Many sperm donors know people who have struggled to fall pregnant, or may have faced their own challenges when starting a family, and would now like to help others in similar circumstances. This often includes gay men who may have required donor eggs and a female surrogate in order to start their own family. Donating can be incredibly rewarding, especially when you know from your own experience how much of an impact you are having on someone else’s life.

A few things to weigh up before becoming a sperm donor

Before becoming a sperm donor, there are a few things to be aware of:

Sperm donors do not have any parental rights nor parental responsibilities

When donation occurs through a registered IVF clinic, sperm donors have no parental rights nor reponsibilities to any children born from their donated sperm. You can be reassured that the child’s legal parents are entirely responsible for raising the child, including all financial costs.

A child may contact their sperm donor once they turn 18

In Australia, children born from donated sperm have the right to obtain their sperm donor’s contact details once they turn 18. Not all children choose to, but if they do get in touch with you, you still have no legal obligation as a parent. However, you may decide that you too would like some involvement in the child’s life.

A sperm donor can also request contact with a child once they turn 18

As an anonymous sperm donor, you also have the option of applying for information about any children conceived from your sperm once they turn 18. If you do so, the child will be informed of your request – they will then let you know if they would like any contact with you and the type of contact they are comfortable with.2

Sperm donors are not paid

In Australia, it is illegal for donors to receive a payment for their sperm. However, you may be entitled to compensation for certain expenses associated with providing the donation, such as medical or travel expenses.

How do I go about becoming a sperm donor?

There are a couple of ways you can donate sperm:

1. Donate to someone you know

You might have a friend who is struggling with fertility, is single or is in a same-sex relationship. In these cases you can choose to donate your sperm to that person or couple specifically, using a fertility clinic as an intermediary.

2. Donate anonymously to a sperm bank

Many people are unable to find a sperm donor using their own personal contacts, e.g. family or friends. In this case, they can access sperm from an anonymous donor via a registered sperm bank (usually associated with their fertility or IVF clinic). By donating your sperm to one of these banks, you can help up to 10 women or couples become pregnant. You can donate a sperm sample one or more times, after which your sperm will be frozen and stored for future use.

What’s involved?

At Newlife IVF, we aim to make donating as easy as possible for you. Five simple steps are involved, four of which can be completed on the same day at our Box Hill fertility treatment centre:

  1. Meet with our counsellor who will ensure you understand your legal rights
  2. Meet with one of our doctors who will take your medical history (for the recipient’s records) and order the required blood tests and semen analysis
  3. Have your blood taken by our on-site pathology team
  4. Donate your sperm using our private, on-site sperm collection amenities
  5. Repeat blood test 3 months later.

Your donated sperm will be quarantined until both your semen analysis and 3-month blood tests are given the all clear. At this point, your frozen sperm become part of our sperm bank. Women and couples requiring donor sperm will be able to choose sperm from you or our other donors based on information we supply to them about each available donor, e.g. physical characteristics, medical history, hobbies/interests, the reasons you give for becoming a donor. As such, we welcome sperm donors from all nationalities and cultures to ensure that women and couples have sufficient choice based on their own nationality and culture.

Your frozen sperm may be stored for years before it is used and it may only be used once or many times – up to the 10 family limit that exists in Victoria. A woman or couple may even choose to access your sperm a second or third time in order to complete their family and maintain genetic lineage between siblings.

Your sperm can only be frozen for up to 10 years. After this time, any remaining sperm are discarded.

Ready to donate life?

Newlife IVF is a doctor-owned specialist fertility centre in Melbourne that provides single women, heterosexual and same-sex couples across Victoria with the extra help they need to conceive. We are very welcoming of new sperm donors, including single men, fathers and gay individuals or couples. If you are considering becoming a donor, please call us on (03) 8080 8933 so we can give you all the facts about sperm donation and tell you how you can best help others to create the family they are dreaming of.

Further reading

  1. Sperm donor information pack, Sperm Donors Australia
  2. Old sperm and international imports: Victoria has a donor shortage (The Age news article)
  3. More Victorian women choosing to be single mothers (The Sydney Morning Herald news article)

* Become a donor with Newlife IVF

References

  1. Bossema ER, Janssens PMW, Landwehr F et al. Acta Obstetricia et Gynecologica Scandinavica 2013; 92:679–85. ↩
  2. The family law implications of early contact between sperm donors and their donor offspring. Australian Institute of Family Studies website (accessed online October 2019). ↩

IVF success rates – what do the numbers really mean?

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In 2017, the number of IVF births in Australia and New Zealand was the highest in IVF’s 40-year history – for every 100 treatment cycles started, 18 babies were born.1

However, the likelihood of success is different for everyone and is particularly influenced by the age of the woman. This means that when you are reviewing IVF success rates – at either a clinic or population level – you should look at data specific to your age group. For example, for women aged younger than 30 years, the live birth rate per fresh embryo transfer (using the woman’s own embryos) was 38.5% in 2017 but this figure dropped to 23.7% for women aged 35–39 and 8.9% for women aged 40–44.1 In 2017, the average age of women undergoing IVF and using their own eggs was 35.7 years while the average age of women undergoing IVF using donor eggs or embryos was 40.3 years.1

IVF success rates are not represented as a single percentage probability. Instead, there are several different figures that clinics may use to report their success rates and the different terms can be confusing. For example, you might wonder what the difference is between a ‘clinical pregnancy rate’ and a ‘cumulative pregnancy rate’, or why there are generally more births per ‘egg collection’ than there are per ‘embryo transfer’.

This article provides an overview of the different figures you might see and what they mean. Before reading the rest of this article, you may find it helpful to refamiliarise yourself with the different steps that make up an IVF treatment cycle.

Live births/pregnancies per treatment cycles commenced

An IVF treatment cycle starts with hormonal stimulation – when you start taking medicine after your period to encourage your ovaries to produce lots of eggs. The IVF treatment cycle ends when a fertilised egg (now called an embryo) is transferred back into your womb in the hope that it will successfully implant in the wall of the uterus, thereby establishing a pregnancy.

The number of live births/pregnancies per treatment cycles commenced describes the number of pregnancies and live births achieved for women that started an IVF cycle (with the intention of a pregnancy, not just to freeze eggs), regardless of whether or not they progressed to subsequent steps of the cycle. So this figure includes cycles that were started, but were subsequently cancelled, or where there were no eggs to collect or no suitable embryo to transfer.

In 2017, 22.9% of initiated cycles resulted in a clinical pregnancy* and 18.1% in a live birth.1 The disparity between the two figures is due to miscarriage or stillbirth.

*A clinical pregnancy is where baby’s heart was heard on ultrasound, usually at around 7 weeks, i.e. not just a positive blood (hCG) test.

Live births/pregnancies per egg retrieval

Measuring the number of live births or pregnancies per egg collection, indicates how successful IVF is in woman who proceeded as far as egg collection.

In 2017, the overall clinical pregnancy rate was 43% per egg retrieval cycle, with a live birth rate of 34%. These figures include cycles where no eggs could be collected (e.g. due to a lack of eggs), as well as cycles where eggs were retrieved but they did not result in embryos for transfer.

*You may also see egg collection referred to as egg retrieval, oocyte pick-up or OPU.

Live births/pregnancies per embryo transfer

Embryo transfer is a critical step in the IVF process, where the developing embryo (fertilised egg) is transferred back into the woman’s womb (uterus). Unfortunately, success rates per embryo transfer can be misleading, because the success of this step is highly dependent on the quality of the embryo, and whether the embryo is transferred fresh or frozen first, then thawed.

These days, embryos may also be genetically screened before transfer, in order to select the highest-quality embryo available for transfer, thereby increasing the likelihood of a successful pregnancy. This type of screening is not recommended for everyone; moreso for older women and/or women who have experienced recurrent miscarriage or multiple, failed IVF cycles. Where genetic screening has been employed, the pregnancy rate per embryo transfer is likely to be higher – and is one of the key reasons why IVF success rates have improved over recent years. However, this means that this figure may not be a good reflection of your own chances of success.

In 2017, the overall rate of pregnancy for cycles reaching embryo transfer was 33.9%, with a live birth rate of 26.8%.1

Implantation rate

The implantation rate describes the number of pregnancy sacs seen given the number of embryos transferred in an IVF treatment cycle. An embryo transfer is considered successful when the embryo implants, i.e. physically attaches itself to the wall of the womb. However, the implantation rate does not tell us how likely these embryos are to go on and result in a clinical pregnancy or live birth.

Live births/pregnancies per implantation

The live births or pregnancies per implantation indicates the percentage of women that went on to achieve a clinical pregnancy or live birth after an embryo had successfully implanted following its transfer into the womb.

The cumulative live birth or clinical pregnancy rate

The cumulative rate for live births or clinical pregnancies is likely to be higher than all the other figures we have described so far. This is because it measures results over multiple IVF attempts, meaning that compared to a single cycle, there are more opportunities for success. The cumulative rate can be measured against either a predefined number of IVF cycles, or it can be measured against the total number of cycles that were attempted by each person.

Which measure of IVF success is most important?

The IVF success rate that is most relevant to you will depend on your individual circumstances, including your age and whether you have had IVF before – and if you are in a cycle right now, what stage of the IVF cycle you have progressed to.

If you are just starting to think about IVF and have not begun treatment yet, then the cumulative live birth rate can help you understand the average success rates for people after their IVF journey is complete.

If you have had one unsuccessful cycle of IVF so far, the cumulative live birth rate can give you an idea of your chance of success if you go on and have additional cycles.

However, the cumulative rate (and other success rates mentioned here) do need to be interpreted with a high degree of caution, because numerous factors influence a couple’s chance of success with IVF.

What else do you need to take into account when interpreting success rates?

Not all IVF cycles are the same. When interpreting data, you should check whether advanced scientific techniques such as ICSI, IMSI or pre-implantation genetic screening were used, and whether the data pertains to fresh versus frozen embryo transfers. This will enable you to review success rates for IVF treatment cycles that most closely resemble your own.

If you are looking at overseas data, keep in mind that single embryo transfer is considered best practice in Australia (in an effort to avoid the risks associated with multiple pregnancies). However, international clinics may offer multiple embryo transfers (transferring more than one embryo into the womb at a time), in which case their IVF success rates per embryo transfer may appear higher.

To gain an understanding of how successful IVF is in Australia, you may like to review this national data collated by The University of NSW.

Weighing up your chance of success?

To get a realistic understanding of your chance of success, it’s best to consult a fertility specialist, so you can receive advice specific to your personal circumstances. If you are looking for a way forward but are not sure where to start or what to try next, you can book an appointment with Nicole, Martin, Chris, Sameer or Hugo by calling (03) 8080 8933 or by booking online. We welcome women and couples who are just starting to consider their fertility treatment options, as well as those who may be seeking a second opinion after treatment elsewhere.

Further reading

References

  1. Australian & New Zealand Assisted Reproduction Database (ANZARD). Assisted Reproductive Technology in Australia & New Zealand 2017 (report). Available at https://npesu.unsw.edu.au. Last accessed 29 October 2019. ↩ ↩

My doctor says we need ICSI – how will this improve our chances of a successful IVF cycle?

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The traditional IVF approach is to allow this meeting to take place ‘naturally’, albeit in a laboratory dish: the woman’s egg is placed in a special culture medium with a prepared semen sample containing thousands of sperm. The fittest sperm fertilises the egg, mimicking what would normally happen in the woman’s reproductive tract.

As its name suggests, ICSI is far more precise. Rather than leaving the egg and sperm to meet of their own accord in a laboratory dish, this technique allows us to directly inject a single sperm into a woman’s egg – thereby, overcoming any issues that may be getting in the way of a sperm and an egg meeting and coming together naturally. Here, we consider some of the reasons why ICSI may be considered during IVF and what specific fertility problems it can help overcome.

Who is ICSI suitable for?

When a couple is experiencing difficulties getting pregnant, it can be easy to focus solely on the woman’s fertility. However, a male factor contributes to infertility in approximately 40% of couples who fail to conceive.1 ‘Male factor infertility’ typically involves an alteration in the number, shape and/or movement of the man’s sperm, all of which can affect the sperm’s ability to fertilise an egg the natural way. ICSI is most commonly used to help overcome these types of sperm-related issues.

ICSI may also sometimes be offered if a woman has very few eggs available (e.g. due to age). In this case, ICSI is used to increase the chances of successful fertilisation, thereby lowering the risk that the woman runs out of eggs before she achieves a successful pregnancy through IVF.

ICSI may also be recommended if one or more previous standard IVF cycles were not successful due to failed fertilisation, or if the reason for cycle failure is unclear but a sperm-related issue is suspected despite a normal semen analysis.2

A checklist for fertile sperm

If your doctor suspects male factor infertility could be affecting your chances of pregnancy, they will usually suggest a semen (sperm) analysis. This is the main method used to test male fertility. During the analysis, a number of different factors that could be affecting your ability to conceive naturally are studied, including:

  • The volume of semen, which needs to be sufficient to transport sperm into the female reproductive tract
  • The sperm concentration and total sperm count, which affect the likelihood that enough sperm will reach the egg in order for one to fertilise it
  • The physical shape of the sperm, as abnormally shaped sperm can have difficulty swimming to the egg or penetrating the egg’s outer layer
  • The motility of the sperm (i.e. how well it can swim) – if large numbers of sperm in the sample are ‘weak swimmers’, then a natural pregnancy will be more difficult to achieve.

Your specialist might also recommend additional testing for:

  • Sperm DNA damage or fragmentation: sperm with damaged or fragmented DNA have a reduced chance of fertilising an egg
  • Sperm antibodies, which if present, can attack and impair sperm function.

Depending on your results, your doctor may then order follow-up tests to make sure the results are accurate and/or to see if anything else is preventing the semen from doing its job.

Once the tests are complete, your specialist will discuss your results with you and explain what your options are, including whether ICSI is likely to increase your chances of successful fertilisation and the overall success of your IVF treatment cycle.

Success rates with ICSI

Because of ICSI, many previously infertile men now have a good chance of fertilising eggs with their sperm. With some couples, pregnancy rates as high as 45% have been achieved with ICSI.3 However, rates this high are not always possible because of other factors, including age and egg quality.

The fertilisation of an egg and its subsequent development into a growing embryo is a complicated process, and there are many reasons why IVF may not be successful, even with the assistance of ICSI. To aid our success rates at Newlife IVF, we:

  1. Ensure an egg is suitable for fertilisation prior to ICSI: Using polarised light microscopy, we assess a structure inside the eggs called a ‘spindle’. We call this ‘egg spindle visualisation’. This allows us to identify if an egg is at a certain stage of development (called metaphase II) and therefore, in optimal condition for fertilisation via ICSI.
  2. Select the healthiest-looking sperm for ICSI: If the genetic information in the sperm has been damaged, or if the sperm is unable to use its DNA correctly, then there is a risk that development of the embryo will fail, even if it has been successfully fertilised via ICSI.4 A number of factors can increase this risk, such as smoking and older age.5,6 It’s not currently possible to know if the sperm we choose for ICSI is completely free of genetic defects. However, by using an advanced imaging system with an extremely high-powered microscope, we are able to study the structure of individual sperm, helping us to select the optimum sperm to inject into an egg. Sometimes, we may also use another technique, called intracytoplasmic morphologically selected sperm injection (IMSI), to help us pick out a healthier sperm based on its shape. A DNA test can also provide us with more details about sperm quality.
  3. Assess the best position to inject the sperm into the egg: Our extremely high-powered microscope also allows us to very precisely inject the selected sperm into the egg, such that we avoid an important structure inside the egg called the spindle. Research has shown that injecting eggs away from the spindle results in higher fertilisation rates and better embryo quality.

Still have questions?

If you are concerned about the possibility of male factor infertility or would like more information about the role of ICSI in an IVF treatment cycle, you can make an appointment with one of our fertility specialists by calling Newlife IVF on (03) 8080 8933. You can also book online via our appointments page.

References

  1. Agerwal A et al. Reprod Biol and Endocrinol. 2015;13:37–46. ↩
  2. Palermo GD et al. Sem Reprod Med. 2015;33:92–102. ↩
  3. Palermo GD et al. Sem Reprod Med. 2009;27:191–201. ↩
  4. Colaco S & Sakkas D. J Assisst Reprod Genet. 2018;35:1953–1968. ↩
  5. García-Ferreyra J et al. Clin Med Insights. Rep Health 2015;9:21–27. ↩
  6. Zini A & Sigman M. J Androl 2009;30:219–229. ↩

Improving your fertility – top tips for men

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The most common fertility issues males encounter include a physical obstruction to the passage of sperm (the sperm simply can’t get to the woman’s egg), problems with sperm production or function (a low sperm count or large numbers of sperm with abnormal shape or movement), functional issues (such as impotence) and hormonal problems (which may impact the production of sperm and/or your libido).

Male factor infertility is more common than you may think – it plays a role in over a third of cases where couples can’t conceive, and affects one in 20 men.1,2

However, beyond a specific medical or physical problem, there are also certain diet and lifestyle changes you can make as a man to improve your overall fertility and chances of conceiving. This is because what we eat and how we live can actually have a big impact on our sex hormones and sperm quality, as well as our libido (sexual drive).

Below, we describe some adjustments you can make to your daily routines to help improve your fertility and overall reproductive health.

Exercise regularly

male in exercise shirt and headphones smiling with waterfront in backgroundNumerous studies have shown that exercise can boost testosterone levels.3 Testosterone is the key male sex hormone that regulates fertility. It is mainly produced in the testicles and is linked to both the development of sperm and sexual function.

It’s also important to be aware that exercising too much can sometimes have the reverse effect and lead to a reduction in testosterone levels. Taking zinc supplements can help mitigate this effect; however, in general you should aim to exercise regularly but not excessively.

Quit smoking

We all know that smoking is bad for our health but what many men don’t know is that smoking can affect every stage of the reproduction process in men. This includes the development of the DNA (genetic material) in sperm, as well as the production of important reproductive hormones. Men who smoke may also experience difficulties in getting and maintaining erections because smoking can cause damage to the small blood vessels that supply the penis with blood.

There is now extensive evidence that smokers are more likely to have fertility problems and take longer to conceive than non-smokers.4,5,6 Therefore, the best way to improve your chances of conceiving is to quit smoking. It’s well established that smoking decreases quality of life and shortens lifespan.  As a motivator, think about the child you are hoping to create and how much quality time you hope to spend with them in the future.

Reduce your alcohol intake

Excessive alcohol consumption can harm sperm count, shape and motility (i.e. how well the sperm can ‘swim’).

Studies have found increased sperm abnormalities in men who drink more than three-and-a-half standard drinks per day.7,8 Alcohol can also disrupt testosterone levels and even turn the testosterone precursor chemicals into oestrogen, leading to increased oestrogen levels (and the dreaded ‘man boobs’!).9 Therefore, reducing or even ceasing alcohol intake can improve your reproductive health.

Stop taking recreational drugs or steroids

Taking certain drugs, both legal and illegal, can affect your fertility. The main ones are:

  • Anabolic steroids – often taken to reduce fat and increase muscle mass, these drugs can actually lead to testicular shrinkage and interfere with the hormones that affect sperm production.
  • Marijuana – the psychoactive ingredient in marijuana, THC, can disrupt testosterone production, leading to a lowered libido as well as reduced quantity and quality of sperm.
  • Opioids – both prescription opioids (for treating pain and addiction) and illegal narcotics (such as heroin), can impact male fertility by affecting testosterone levels.
  • Testosterone – replacement testosterone can impair sperm production by blocking the hormonal signals that tell the testicles to make testosterone.

Manage your stress levels

High stress levels, particularly ongoing, can have a negative impact on your fertility by interfering with certain hormones. It is thought that stress may activate steroid hormones involved in the metabolism of proteins, fats and carbohydrates, which may, in turn, affect testosterone levels and the production of sperm.10,11

Get enough sleep

Sleep may be just as important for fertility as other bedroom activities (!), according to a growing body of research. A recent study suggests that 7–8 hours of sleep a night is the ideal, while too little or even too much sleep can reduce your chances of conceiving.12

Eat a healthy diet

A healthy, balanced diet is essential for your overall health. But did you know that choosing the right foods can enhance sperm function and, in turn, your fertility? Nutrients that can improve the quality of your sperm include:

  • Vitamin D (tuna, salmon, cheese, egg yolk)
  • Vitamin E (vegetable oils, nuts, seeds, green leafy vegetables)
  • D-aspartic acid (oysters, avocado, asparagus, oat flakes)
  • Omega-3 fatty acids (mackerel, chia seeds, walnuts, plant oils)
  • L-arginine (pumpkin seeds, turkey breast, chickpeas, seaweed).13,14,15,16

It’s also important to keep your weight in check, as being overweight can reduce your fertility by affecting sperm and leading to hormonal changes.17

The bottom line

If you or your partner are having difficulties conceiving, there are a number of steps you can take as a man to improve your fertility and overall health, thereby maximising your chances of having a baby. Seeking professional help to rule out a specific physical or medical problem is also prudent. At Newlife IVF, we conduct both male and female fertility testing, including the highest quality semen analysis currently available in Victoria.

To make an appointment with one of our fertility specialists or to get a second opinion, call Newlife IVF on (03) 8080 8933. Alternatively, you can book online via our appointments page.

Further reading

References

  1. Hirsh A. BMJ. 2003;32:669. ↩
  2. Winters BR, Walsh TJ. Urol Clin North Am. 2014;41:195­–204. ↩
  3. Kumagai H et al. J Clin Biochem Nurt. 2016;58:1:84–89. ↩
  4. Mitra et al. Syst Biol Reprod Med. 2012;58: 255–262. ↩
  5. Al-Turki HA et al. Urol Ann. 2015;7:63–66. ↩
  6. Cui X et al. Mol Med Rep. 2016;14:753–761. ↩
  7. Jensen TK et al. BMJ Open. 2014;4:e005462. ↩
  8. Martini AC et al. Fert Ster. 2004;82:374–377. ↩
  9. Emmanuele MA et al. Alcohol Health Res World. 1998;22:195–201. ↩
  10. Ragni G, Caccamo A. Acta Eur Fertil. 1992;23:21–23. ↩
  11. IIacqua A et al. Reprod Biol Endocrinol. ↩
  12. Liu MM et al. Med Sci Monit. 2017;23:1842–1848. ↩
  13. Blomberg JM et al. Hum Reprod. 2011;26:1307–1317. ↩
  14. Sedigheh A et al. Int J Reprod Biomed. 2016;14:729–736. ↩
  15. Topo E et al. Reprod Biol Endocrinol. 2009;27:120. ↩
  16. Safarinejad RM. Asian J Androl. 2012;14:514–515. ↩
  17. Martini AC et al. Fert Ster. 2010;94:1739–1743. ↩

If not IVF, then what? Fertility treatments explained

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In vitro fertilisation (IVF) is the most widely known fertility treatment, but it is not the only option available to help couples with fertility issues. This is due to the fact that there are many different reasons why an individual or couple may be experiencing fertility problems and treatment should be tailored accordingly. Thus, fertility treatment actually encompasses quite a wide range of methods, each of which can help people to overcome specific challenges and ultimately, conceive. We explain the different options below, including when they might be suitable.

First-line treatments

Ovulation induction

Ovulation induction may be recommended for women who are not ovulating regularly or who are not ovulating at all, and is commonly used for those suffering from polycystic ovarian syndrome (PCOS).

As its name suggests, ovulation induction involves the woman taking medication to increase the level of follicle-stimulating hormone (FSH) that causes ovulation. These medications may be in the form of tablets (clomiphene or letrozole) or direct injections of FSH. This stimulates the growth of ovarian follicles (fluid-filled sacs containing an egg). Once the follicles are large enough, another hormone is then given to release the egg from the follicle. Couples are advised to have intercourse at this time to increase their chances of conceiving.

Intrauterine insemination (IUI)

Intrauterine insemination (also known as artificial insemination) may be considered when a couple has difficulty having intercourse. It may also be appropriate for women with scarring or defects of the cervix that prevent sperm penetration, and for men with mild reductions in either sperm count or sperm motility (i.e. sperm that don’t move properly) where concentrating the semen sample and placing it in the uterus is likely to be of benefit. IUI may be used in combination with medications that stimulate ovulation – this combination can increase the chance of pregnancy in some cases.

During a treatment cycle, patients are monitored closely with blood tests and ultrasounds. At the time of ovulation, sperm are placed directly through the woman’s cervix and into her uterus (womb) using a long, thin plastic tube that is similar to a straw (hence, the name artificial insemination).

Laboratory treatments

In vitro fertilisation (IVF)

IVF is a form of assisted reproductive technology (ART) in which eggs are retrieved from the body of a woman and combined with sperm outside the body to achieve fertilisation. If this is successful and the fertilised egg continues to develop into an embryo, it is transferred back into the uterus (womb) in the hope that it will implant and grow, thereby achieving a pregnancy.

Intracytoplasmic sperm injection (ICSI)

ICSI is a technique where a single sperm is directly injected into an egg to achieve fertilisation. This technique may be recommended when the male partner in a couple has been diagnosed with fertility issues such as low sperm count, abnormal sperm morphology (shape) or motility (movement), has had a previous vasectomy or an unsuccessful vasectomy reversal. The ‘best’ sperm – based on size, shape and movement – is selected for the ICSI procedure.

Sperm retrieval procedures

Some men have no sperm in their semen (a condition known as azoospermia) due to a sperm production problem or a blockage that prevents the sperm from getting into the semen. These men may need to have sperm taken directly from the testis or the epididymis (a coiled tube that stores sperm and transports it from the testis).

  • Testicular sperm aspiration (TESA) is done by inserting a needle into the testis and taking a small amount of material from the seminiferous tubules – a network of tiny tubes where sperm is produced. The procedure is done using local anaesthesia in an operating theatre.
  • Percutaneous epididymal sperm aspiration (PESA) can be an option for men who have obstructive azoospermia from a previous vasectomy or infection. Under local anaesthesia, a small needle is inserted into the epididymis to extract sperm. PESA is also usually performed in an operating theatre.
  • Microdissection TESE (microTESE) may be used for men who have a sperm production problem. This procedure is done under general anaesthetic. The testis is first opened with a small incision, then an operating microscope is used to identify the seminiferous tubules most likely to contain sperm and take tissue samples from them.

Pre-implantation genetic testing (PGT)

PGT is a way to reduce the risk of an individual or a couple passing on a specific genetic or chromosomal abnormality to their child. It may also be used to check for genetic problems in older women (e.g. over the age of 38 years), women who have experienced several miscarriages, or cases of repeated IVF failure.

In PGT, embryos are produced through the usual IVF process and then cells taken from the embryo are tested for genetic conditions. If the embryo is unaffected, it is then transferred to the woman’s uterus.

Egg or sperm freezing

There are two main reasons for freezing eggs. Some women need to freeze their eggs for medical reasons such as impaired ovarian function or impending chemotherapy or radiotherapy for cancer. Other women choose to freeze their eggs because they want to give themselves the option to have children in later years.

A man may be advised to freeze his sperm if he is about to undergo treatment for cancer, or if he has decided to have a vasectomy but may potentially want to have children later on. Men also can freeze sperm prior to either IUI or IVF if they cannot be present on the day scheduled for the respective ART procedure.

Donor treatments

Donor insemination

Donor insemination may be used as part of IVF for a single woman or for women in a same-sex relationship. The process is the same as artificial insemination, but the sperm used is from a donor rather than a male partner.

Donor insemination may be considered when the male partner does not produce sperm (or the sperm is abnormal) or when there is a high risk of the man passing on an illness or abnormality to a child.

Donor eggs

Donor eggs may be an option when a woman is unable to produce eggs or her eggs are of a low quality. This may be due to age or premature ovarian failure (a condition in which a woman stops producing eggs earlier than usual).

Donor eggs may also be appropriate in cases of recurrent miscarriage or if there is a high risk of the woman passing on an illness or abnormality.

Donor embryos

In some cases, some people choose to donate frozen embryos they no longer need. Treatment using these donated embryos may be suitable for a person or a couple who need both donor sperm and donor eggs.

What is the best option for you?

If you would like advice about the next steps to take on your fertility journey, you can make an appointment with one of our fertility specialists by calling Newlife IVF on (03) 8080 8933 or by booking online via our appointments page. We’ll complete a comprehensive assessment before explaining the options available to you and your partner.

What influences your chance of IVF success?

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The first baby conceived by this method was born in 1978, paving the way for a new era in how babies could be conceived and thus helping to address a range of fertility issues. Since then, the methods and technology used in IVF treatment have significantly improved, success rates have risen, and millions of babies have now been born worldwide using IVF.

IVF may be suitable if you would like to conceive but you or your partner have fertility problems, or perhaps because you want to avoid passing on inherited genetic disorders to your children. Whatever the reason, opting for IVF is a big decision so it is important to understand the factors that may influence the outcome of the procedure.

The likelihood of you having a baby via IVF can be affected by a number of factors – some that you cannot change, such as your age or particular types of fertility problem, and some that are modifiable. Modifiable factors can be medical or lifestyle related. Here, we will explore some of the most important factors that could affect your chances of conceiving with IVF.

Age

Age is well recognised to be one of the most influential factors in predicting IVF success. This is because as a woman ages, both the quantity and quality of her eggs declines.1 IVF technology in the setting of low numbers of eggs and/or poor-quality eggs is much less successful.2

If you receive donor eggs from a younger woman, you can expect to have nearly the same chance of success as women of the age of your donor. This is because younger eggs tend to be of better quality.2

Chromosomal abnormalities (problems with the DNA-containing structures in cells) are one of the major factors contributing to IVF failure and are the reason behind most miscarriages. These abnormalities increase as we age, and at a faster rate in women – by your mid-40s, as many as 75% of the chromosomes in your eggs are likely to have abnormalities.1

Our recommendation is to start IVF sooner rather than later (there is no lower age limit for IVF treatment). Everyone’s body is unique so a comprehensive medical assessment can give a better indication of your chances of conceiving with IVF than your age alone. IVF has been used successfully to help women at all stages of their reproductive life, but it is important to understand that each case is different.

Previous pregnancy or miscarriage

If you’ve previously been pregnant, the likelihood of you having a baby during your IVF treatment may be increased – IVF is recognised as being more effective in women who have previously been pregnant and/or had a live birth.3 On the other hand, if you have had a miscarriage, your chances of success with IVF may be reduced. If you have experienced recurrent miscarriages (three or more pregnancy losses), you might have a particular fertility issue where IVF may not help.

We can help you narrow down the probable causes of pregnancy loss and provide recommendations on the most appropriate course of action.

Type of fertility problem

IVF can be a good option for couples having trouble conceiving as a result of certain fertility problems, such as low numbers of sperm, issues with ovulation, endometriosis or blockages of the fallopian tubes. However, IVF does not work well for everyone.

Some fertility problems respond less well to IVF, including:

  • Poor ovarian response: Sometimes the ovaries do not respond well to fertility medications and therefore can’t produce the multiple eggs that make IVF more effective. This can occur if your ovarian reserve (number of eggs in your ovaries) is low or if they are not responding to the IVF treatment. If this is the case, IVF with your own eggs may not be the best option and you may wish to opt for donor eggs.
  • Duration of infertility: Statistically, couples that have been infertile for longer are less likely to have a baby with IVF.4 If you and/or your partner have had problems with fertility for several years, a health assessment will be necessary to determine whether IVF is suitable for you.
  • Dual infertility: If both you and your partner have fertility problems, the chance of success with IVF may be lower. Male infertility can be challenging to address with IVF, because sperm of impaired quality do not fertilise eggs at the same rates as normal sperm. Careful testing of both partners can give a better idea of whether IVF is the right option for you.
  • Fibroid tumours: Benign fibroid tumours (tissues that grow in and around the wall of the uterus, or womb) are very common, and usually don’t interfere with becoming pregnant. Sometimes, however, they can make it difficult for the embryo to implant and grow properly. These cases can usually be surgically corrected, allowing pregnancy to occur.
  • Uterine abnormalities: Congenital uterine anomalies (i.e. problems with the uterus that develop before you are born) can reduce the chance of a successful pregnancy. Outcomes vary from woman to woman, depending on the type of abnormality, so it is important to have a full health assessment to determine the specific abnormality.

Each case is different, so it is important that you undergo an in-depth consultation and careful testing in order to understand whether IVF is the right option for you.

Lifestyle factors

Lifestyle factors such as nutrition, smoking, and alcohol consumption can affect you and/or your partner’s fertility. Even though many factors influencing IVF success are out of your control, you may be able to improve your chances by understanding and addressing the following factors.

Obesity and nutrition

Being overweight or obese can have an impact on your fertility. Obesity (BMI 30 to 35) has been linked to miscarriage following IVF, and is also associated with reduced pregnancy rates in women and lower sperm quality in men.5 It is thought that an increase in leptin (the hormone secreted by fat tissue) can affect menstruation, in turn leading to worse IVF outcomes.

The ‘Mediterranean diet’, which consists of a high intake of vegetables, legumes and vegetable oils, and a low intake of fast food, has been linked to a higher pregnancy rate and may potentially improve the chances of pregnancy after IVF.6 This could be due to the presence of linoleic acid in vegetable oils, which may be beneficial for the implantation of the fertilised embryo.

Smoking and alcohol

You and/or your partner should quit smoking if you’re considering IVF. Smoking can cause damage to the sperm’s DNA and can affect the reserve of eggs and their ability to become fertilised.7 Smokers often require twice as many IVF cycles to conceive than non-smokers.8 You can also be affected by second-hand smoke – fertility is reduced in women exposed to cigarette smoke from their partners smoking at home.9

Drinking alcohol can also reduce your chances of IVF success, as it affects pregnancy and miscarriage rates. Just one can of beer per day before week 1 of the sperm or egg collection has been linked to reduced IVF success.10 Drinking alcohol when you’re trying to conceive – whether through IVF or not – is not recommended. This is because alcohol can cross the placenta and affect the development of your baby, potentially leading to problems such as fetal alcohol syndrome, stillbirth or physical disabilities.

During an IVF cycle, you should focus on eating healthy, balanced meals. Maintaining a healthy weight is extremely important, and your BMI range should ideally be between 19 and 30 before attempting IVF.Consider reducing your alcohol intake, and if you or your partner smoke, quitting is the best option.

Deciding whether IVF is right for you

When considering your fertility, there is no one-size-fits-all approach. As with all aspects of fertility care, the best decision for you is the one that is personalised to your individual situation.

For more information about IVF, please visit our IVF page. And if you would like to discuss your options with one of our fertility specialists, please call Newlife IVF on (03) 8080 8933 or book online via our appointments page.

References

  1. van Loendersloot LL et al. Hum Reprod 2010;16:577–589.
  2. Sabatini L et al. Reprod Biomed 2008;17:10–19.
  3. Nelson SM, Lawlor DA. PLoS med 2011;8:e1000386.
  4. Roberts S et al. Health Technol Assess 2010;14:1–237.
  5. Fedorcsak P et al. Acta Obstet Gynecol Scand 2000;79:43–48.
  6. Vujkovic M et al. Fertil Steril 2010;94(6):2096–2101.
  7. Frins S et al. Reprod Biol and Endocrinol 2015;13:134.
  8. Younglai EV et al. Arch Environ Contam Toxicol 2002;43:121–126.
  9. Zenzes M et al. Mol Hum Reprod 1998;4:159–165.
  10. Klonoff-Cohen H et al. Fertil Steril 2003;79:330–339.