Frozen embryo transfer (FET) has become a mainstream technique in assisted reproductive technology, offering hope to many couples struggling with infertility.

This procedure involves freezing embryos created during in vitro fertilization (IVF) and transferring them into the woman’s uterus at a later date. While FET has been successful in achieving pregnancy, there have been concerns about its potential association with an increased risk of preeclampsia.

What is Preeclampsia?

Preeclampsia is a disorder that occurs during pregnancy and is characterized by high blood pressure and damage to organs, most commonly the liver and kidneys.

It usually appears after the 20th week of pregnancy and can lead to serious complications for both the mother and the baby. Symptoms of preeclampsia include high blood pressure, protein in the urine, swelling, headaches, and vision changes.

Research on the Link Between FET and Preeclampsia

Several studies have investigated the potential association between FET and the risk of preeclampsia.

While the results have been varied, some researchers have found evidence suggesting a higher risk of developing preeclampsia following FET compared to fresh embryo transfer or natural conception.

A study published in the Journal of the American Medical Association (JAMA) in 2018 analyzed data from over 200,000 pregnancies and found that frozen embryo transfer was associated with a 55% increased risk of preeclampsia compared to fresh embryo transfer. Another study published in the journal Fertility and Sterility found a similar increase in the risk of preeclampsia among women who underwent FET.

However, it is important to note that not all studies have found a significant association between FET and preeclampsia.

A systematic review and meta-analysis published in the British Journal of Obstetrics and Gynaecology analyzed data from multiple studies and concluded that there was no consistent evidence to support an increased risk of preeclampsia following FET.

Possible Explanations for the Link

The exact reasons behind the potential link between FET and preeclampsia remain unclear. However, researchers have proposed several hypotheses to explain this association.

One theory suggests that the hormonal stimulation used during IVF may impact the development of the placenta, leading to an increased risk of preeclampsia.

Another hypothesis is that the freezing and thawing process of embryos may cause epigenetic changes that affect the implantation of the embryo and subsequent placental development.

Furthermore, it is also possible that factors related to the underlying infertility, rather than the FET procedure itself, contribute to the observed increased risk of preeclampsia.

Conditions such as polycystic ovary syndrome or endometriosis, which are associated with infertility, have also been linked to an increased risk of preeclampsia.

Minimizing the Risk of Preeclampsia

While the link between FET and preeclampsia is not yet fully understood, there are steps that can be taken to minimize the risk of developing this condition during pregnancy following FET.

Regular prenatal care and monitoring are essential to detect any signs of preeclampsia early on.

This includes regular blood pressure checks, urine testing for protein, and regular ultrasounds to monitor the baby’s growth and the development of the placenta.

Lifestyle factors can also play a role in reducing the risk of preeclampsia.

Maintaining a healthy weight, exercising regularly (under medical guidance), and following a balanced diet rich in fruits, vegetables, and lean proteins can help promote a healthy pregnancy and reduce the risk of preeclampsia.

Conclusion

While there have been studies suggesting an increased risk of preeclampsia following FET, the evidence is not yet conclusive.

It is important for couples considering FET to discuss this potential risk with their healthcare provider and to weigh the benefits of the procedure against the potential risks.