RECENT evidence has emerged from a large cohort study of the national in vitro fertilisation (IVF) registry of France, suggesting a link between embryo freezing and blood pressure problems during pregnancy. The study, which included almost 70,000 pregnancies between 2013 and 2018, found a higher risk of conditions including pre-eclampsia and hypertension in pregnancies derived from frozen-thawed embryos. This research was presented at the online annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) by Sylvie Epelboin of the Hôpital Bichat-Claude Bernard, Paris, France.
The results of the study showed an increased risk of developing vascular pathologies in frozen-thawed embryo IVF pregnancies, particularly in those during which the uterus was prepared for implantation using hormone replacement therapies (HRT). Epelboin explained that the HRT given prevents ovulation, therefore suppressing the formation of the protective corpus luteum.
Although the risk of developing disorders such as pre-eclampsia are increased in frozen-thawed embryo IVF, the risk of maternal morbidity is generally much higher in fresh embryo transfers. The study split the group of pregnancies into three groups; those derived from frozen embryo transfer, those from frozen embryo transfer with HRT (artificial), and those derived from fresh embryo transfers. Results indicated a higher incidence of pre-eclampsia in the artificial group compared to the remaining groups; similar rates were observed in relation to the development of pregnancy-induced hypertension.
Epelboin and colleagues established that the use of frozen-thawed embryos together with HRT is significantly linked to an increased risk of developing vascular pathologies during pregnancy. There has been an increase in the use of frozen embryos in recent years due to their reduced risk of hyperstimulation. It was concluded by scientists involved in this study that the observed risks of vascular disorder development do not outweigh the benefits of frozen embryo transfer IVF.