Can freezing IVF embryos reduce pregnancy complications?

Dr Lucy Higgins, Professor Daniel Brison, Dr Mark Dilworth, Professor Ed Johnstone

Babies conceived by IVF have a higher risk of complications and stillbirth. Our scientists are studying why freezing an IVF embryo before it is transferred into the mother’s womb could help to reduce these risks.

Start: April 2020

End: April 2022

Why do we need this research?

Couples who can’t get pregnant naturally can opt for in vitro fertilisation (IVF), where the egg is fertilised by sperm outside the body. However, we know that IVF pregnancies have a higher chance of complications, including stillbirth and death shortly after birth.

We need to understand why this is the case, and what can be done to reduce the risks for babies conceived by IVF.

What’s happening in this project?

After IVF, embryos can either be transferred ‘fresh’ into the mother’s womb, or frozen first and transferred later. Researchers have noticed that babies from frozen IVF embryos tend to grow faster during pregnancy compared to babies from fresh IVF embryos. However, it is not clear why.

A lot of pregnancy complications are caused by problems with the placenta. This has led our researchers to believe there might be differences in the placentas of babies born from ‘fresh’ IVF embryos versus those from frozen embryos. Our scientists will test this theory in this project.

The team will study the placentas of babies born following IVF treatment – some after fresh embryo transfer and others after the embryos are frozen. They will be looking at the weight and size of the placenta, as well as studying the cells and blood vessels inside it. The team will also be asking the mothers for blood samples throughout pregnancy, to look for hormones in the blood which are related to how blood vessels and the placenta develop.

What difference will this project make?

This project will help us to understand why IVF pregnancies have a higher risk of complications. Freezing IVF embryos could become a standard part of IVF treatment and help to prevent pregnancy complications, stillbirth and miscarriage.

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