The rise of sub-fertility – are you affected? - Newlife IVF Melbourne

The rise of sub-fertility – are you affected?

4 October 2019

Dr Nicole Hope

When an individual or couple is experiencing a significant delay in falling pregnant, we use the term sub-fertility.1 Being subfertile rather than infertile means that it's still possible to conceive naturally, but it takes longer than average. So why does it take some people longer to fall pregnant than others?

1Our fertility is influenced by many factors including our age, genetics, lifestyle, recent illness and contraception use.2 For example, did you know that a man’s sperm count can temporarily decrease following a virus and take 3–6 months to recover?

Indeed, fertility often reflects our overall health, so if you are experiencing a delay in falling pregnant, a good first step is to review your lifestyle and identify any risk factors or habits that could be impacting you and/or your partner’s fertility. Taking steps to reduce these risk factors, while also learning how to increase the odds of conception (e.g. through ovulation tracking and timed intercourse), may be all that’s required for you to fall pregnant naturally.

The rise of sub-fertility

While there are specific medical problems that can cause fertility issues, the number of couples experiencing sub-fertility – rather than infertility due to an obvious medical cause – is increasing. Diet and other lifestyle factors have been implicated as key reasons for couples’ waning fertility. The good news is that research clearly shows that we can optimise our reproductive health and fertility by making positive lifestyle changes. For the most part, this means being more mindful about how we treat and care for our bodies each day – from the food, drink and other substances we consume to how much exercise and rest we get. Even a few small changes can make a significant difference to your odds of conception.

Get started with our fertility-wise checklist

The below checklist can help you identify what changes you and your partner can make to optimise your fertility and increase your chances of falling pregnant sooner:

1. Are you under or overweight?

Carrying too little or too much weight can cause sub-fertility by altering the balance of your reproductive hormones.3,4 This, in turn, can affect ovulation, as well as sperm production and function. Research has shown that if a woman is overweight, even a small drop in weight (5%) can significantly improve her chances of conceiving.5

2. Do you #eatforfertility?

A poor diet can also play havoc with the body’s hormones and cause problems with ovulation, as well as the number and quality of sperm.6 You can learn more about how diet can affect fertility from our fertility specialist, Dr Chris Russell.

3. What’s hidden in your drinks?

Soft drinks, energy drinks, fruit juice and iced teas are all loaded with sugar. Just like the wrong foods, the wrong drinks can also cause weight gain and upset your hormones. Swapping out these drinks for herbal teas and water is a good strategy for removing sugar from your diet. When it comes to coffee and other caffeinated beverages, low to moderate levels of consumption may be OK. However, higher levels of caffeine consumption have been linked to an increased risk of sub-fertility and miscarriage in women.7,8 Given these risks, the safer bet for women is to limit consumption of caffeinated drinks to one per day.

4. How physically active are you?

Exercise is a key component of managing weight. Moderate exercise increases the chance of having a baby among women who undergo assisted reproductive techniques (ART).9 In contrast, a large amount of high intensity exercise may actually reduce fertility, so it’s a good idea to avoid this type of exercise while trying for a baby – this is true for both men and women.10,11

5. Are you a smoker?

Men and women who smoke are more affected by sub-fertility than non-smokers, so if you smoke it may take longer for you to get pregnant. This is because smoking affects every stage of the reproduction process, reducing your chances of both natural pregnancy and IVF success.12,13 There is no safe limit for smoking – the only way to remove this risk factor is to quit.

6. How much alcohol do you consume?

Research shows that even drinking lightly can increase the time it takes to fall pregnant.14 For women who are planning a pregnancy, the safest option is to abstain from all alcohol. For men, heavy drinking can cause impotence, reduce sex drive (libido) and affect sperm quality – we recommend following the Australian safe drinking guidelines and limiting your intake to no more than two standard drinks a day.15

7. Could other substances be causing you harm?

For both men and women, taking cocaine, heroin, ecstasy and marijuana can reduce the chance of having a baby. Taken over a long period of time, recreational drugs can cause permanent problems with the reproductive system and infertility. Taking anabolic steroids can also affect the production of sperm – in fact, it can take up to two years for sperm to return to normal after stopping steroids. Some medications, including treatments for hypertension and depression, may also affect fertility.16 Your doctor is the best person to advise whether a medication can affect your fertility and if other treatment options are available.

8. Could stress be playing a role?

If you encounter a lot of stress in your life, then there’s a chance your reproductive system isn’t working as well as it could be.17,18 You can learn more about the link between stress and sub-fertility by reading this article by Newlife IVF fertility specialist, A/Prof Martin Healey.

9. Have you reduced your exposure to potentially harmful chemicals?

Studies show that some chemicals (referred to as ‘endocrine disrupting chemicals’) can reduce the quality of sperm and eggs, affecting a couple’s chances of conceiving. While it is impossible to completely avoid these chemicals, you can reduce your exposure to them. The Your Fertility website has detailed information on the types of chemicals that affect fertility, where they are found, and what you can do to avoid them.

10. Are you getting enough sleep?

There is increasing evidence to suggest that sleep may have an impact on fertility. A recent study found that men who went to bed earlier (before 10.30pm) and slept longer (more than seven hours a night) were more likely to have good quality sperm.19 Similarly, another study showed that women with insomnia were more than four times as likely to experience infertility than their peers who slept well.20

When should you seek help?

Women under 35 are advised to seek help after 12 months of trying for a baby. As fertility declines with age, women over 35 are advised to seek help earlier, after 6 months of trying.

If you are experiencing a delay in falling pregnant and would like further advice, you can make an appointment with one of our specialists by calling Newlife IVF on (03) 8080 8933. You can also book online via our appointments page.


  1. Gnoth CE, Godehardt P, Frank-Herrmann K et al. Definition and Prevalence of Subfertility and Infertility. Human Reproduction 2005; 20 no. 5: 1144–47. 
  2. Axmon A, Rylander L, Albin M et al. Factors Affecting Time to Pregnancy. Human Reproduction 2006; 21 no.5: 1279–84. 
  3. Ling PR. Focus on Obesity Research. New York: Nova Publishers, 2005. 
  4. Durairajanayagam D. Lifestyle Causes of Male Infertility. Arab Journal of Urology 2018; 16 no.1: 10–20. 
  5. Clark AM, Ledger W, Galletly C et al. Weight Loss Results in Significant Improvement in Pregnancy and Ovulation Rates in Anovulatory Obese Women. Human Reproduction 1995; 10 no.10: 2705–12. 
  6. Gaskins AJ, Chavarro JE. Diet and Fertility: A Review. American Journal of Obstetrics and Gynecology 2018; 218 no.4: 379–389. 
  7. Chen LW, Yi W, Neelakantan N. et al. Maternal Caffeine Intake during Pregnancy and Risk of Pregnancy Loss: A Categorical and Dose–Response Meta-Analysis of Prospective Studies. Public Health Nutrition 2016; 19 no.7: 1233–44. 
  8. Florack EIM, Zielhuis GA, Rolland R. Cigarette Smoking, Alcohol Consumption, and Caffeine Intake and Fecundability. Preventive Medicine 1994; 23 no.2: 175–80. 
  9. Rao M, Zeng Z, Tang L. Maternal Physical Activity before IVF/ICSI Cycles Improves Clinical Pregnancy Rate and Live Birth Rate: A Systematic Review and Meta-Analysis. Reproductive Biology and Endocrinology 2018; 16 no.1:11. 
  10. Vaamonde D, Agarwal A, du Plessis SS et al. Impact of Physical Activity and Exercise on Male Reproductive Potential: Semen Alterations. In: Vaamonde D, ed. Exercise and Human Reproduction: Induced Fertility Disorders and Possible Therapies. New York: Springer, 2016: 101–24. 
  11. Morris SN, Missmer SA, Cramer DW et al. Effects of Lifetime Exercise on the Outcome of in Vitro Fertilization. Obstetrics & Gynecology 2006; 108 no.4: 938–945. 
  12. Mínguez-Alarcón L, Chavarro JE, Gaskins AJ. Caffeine, Alcohol, Smoking, and Reproductive Outcomes among Couples Undergoing Assisted Reproductive Technology Treatments. Fertility and Sterility 2018; 110 no.4: 587–92. 
  13. Hart RJ. Physiological Aspects of Female Fertility: Role of the Environment, Modern Lifestyle, and Genetics. Physiological Reviews 2016; 96 no.3: 873–909. 
  14. Fan D, Li L, Xia Q et al. Female Alcohol Consumption and Fecundability: A Systematic Review and Dose-Response Meta-Analysis. Scientific Reports 2017; 7 no.1: 13815. 
  15. Ricci E, Al Beitawi S, Cipriani S et al. Semen Quality and Alcohol Intake: A Systematic Review and Meta-Analysis. Reproductive BioMedicine Online 2017; 34 no.1: 38–47. 
  16. Alvarez, S. Do Some Addictions Interfere with Fertility? Fertility and Sterility 2015; 103 no.1: 22–26. 
  17. Nargund VH. Effects of Psychological Stress on Male Fertility. Nature Reviews Urology 2015; 12 no.7: 373–82. 
  18. Vartiainen H, Suonio S, Halonen P et al. Psychosocial Factors, Female Fertility and Pregnancy: A Prospective Study — Part II: Pregnancy. Journal of Psychosomatic Obstetrics & Gynecology 1994; 15 no.2: 77–84. 
  19. Hvidt J, Knudsen UB, Zachariae R et al. Association of Sleep Quality, Bedtime, and Sleep Duration with Semen Quality in Males Seeking Fertility Treatment. In ESHRE, 2019. 
  20. Wang I, Liu Y, Peng C et al. Non-Apnea Sleep Disorder Increases the Risk of Subsequent Female Infertility—A Nationwide Population-Based Cohort Study. Sleep 2017; 41 no.1:186-189. 

The information on this page is general in nature. All medical and surgical procedures have potential benefits and risks. Consult your healthcare professional for medical advice specific to you.