How embryos develop – from egg retrieval to blastocyst

After retrieval, the egg and sperm are combined, and if fertilisation is successful, your embryo spends the first few days growing in the lab under the expert care of our team. This blog will help guide you through these early embryo development steps before transfer or freezing.

Factors affecting embryo development

Embryo development is a complex process that requires a combination of genetic, environmental and physiological factors to progress successfully. To achieve good embryo development, we require:

Healthy egg and sperm

The egg and sperm provide the genetic blueprint for development. Each embryo needs a complete set of 46 chromosomes – 23 from the egg and 23 from the sperm. Some embryos inherit incorrect genetic instructions that can impact embryo development and make it harder for them to divide and grow as expected.

Mitochondrial energy

Embryos need energy to divide and grow, which is provided by mitochondria (tiny energy-producing structures in cells). Poor mitochondrial function can slow or stop embryo development.
Efficient metabolic function:

An embryo’s metabolic function provides both energy and the building blocks needed for development. This includes the creation of protein and fats, and the removal of waste products that can be toxic to the embryo. Together, these provide what the embryo needs for growth, cell division and viability.

Timely cell division

Embryos should ideally divide at a regular pace (2-cell, 4-cell, 8-cell, etc.). Uneven and/or delayed division can mean the embryo is of suboptimal quality and may not develop as expected.

Embryonic genome activation

Around Day 3 (see diagram below), embryos start using their own DNA instead of relying on maternal DNA (genetic code from the egg). If this DNA transfer is inadequate, interrupted or missing, this can slow or stop the development of an embryo.

Stable conditions

Embryos need the right temperature, oxygen and pH balance to grow. These factors are carefully assessed and monitored continuously in the laboratory environment.

Difficulties or inaccuracies in any of these processes can affect the way an embryo grows and can impact whether an embryo will reach the blastocyst stage (where it has divided into many cells), making it suitable for transfer or freezing.

Safeguarding your embryos is our highest priority

We understand how important every embryo is to your journey. That’s why we use the most advanced technology and scientifically proven methods to create the ideal environment for embryo development. From carefully performing every procedure to closely monitoring each embryo’s progress, our highly trained embryologists work tirelessly to give each embryo the best possible chance to grow and thrive.

We maintain strict laboratory conditions, including precise temperature, humidity and air quality control to mimic the natural environment as closely as possible. Our team carefully observes each embryo’s development at every stage. Even though not all embryos will reach the blastocyst stage, please know that we do everything in our power to maximise their potential. Your dream of building a family is at the heart of everything we do, and we are committed to providing the best possible care every step of the way.

If you have any questions about embryo development or your fertility journey, please reach out to Newlife IVF. In the meantime, let’s walk through the different stages of embryo development to help you better understand the process