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June 30, 2021: A large cohort study drawn from France’s national IVF registry, which included nearly 70,000 pregnancies born after 22 weeks gestation between 2013 and 2018, found a higher risk of preeclampsia and hypertension in derived pregnancies of thawed frozen embryos. This risk has been found to be significantly higher in treatments in which the uterus has been prepared for implantation with hormone replacement therapies. The results confirm with real data what has been observed in subgroups of patients in other studies.
The results are presented today by Dr Sylvie Epelboin from Bichat-Claude Bernard Hospital, Paris, at the ESHRE annual online meeting. The study was carried out on behalf of the Mother-Child Health Network after ART, of the French Biomedicine Agency. She said the results highlight two important considerations in IVF: the potentially harmful effects on vascular pathologies of high and prolonged doses of hormone replacement therapy used to prepare the uterus for implantation of frozen-thawed embryos; and the protective effect of a yellow body (1), present in natural or stimulated embryo transfer cycles. Hormone replacement therapy administered to prepare the uterus for embryo transfer, explains Dr Epelboin, suppresses ovulation and therefore the formation of the corpus luteum.
The risk of preeclampsia and other pregnancy-related pregnancy disorders has been increased in a growing number of studies of IVF freezing. (2) However, it is known that the overall risks of maternal morbidity are generally lower in pregnancies resulting from freeze transfer embryos than in those resulting from fresh transfers – except with regard to the risk of preeclampsia. While some studies have observed such risks in frozen embryo transfers, few studies, according to Dr Epelboin, have compared these “maternal vascular morbidities with the two hormonal environments that preside over the early stages of embryonic development”.
This study divided the cohort of pregnancies resulting from IVF and ICSI in the French national database into three groups of comparison singletons: those resulting from the transfer of frozen embryos in a natural “ovulatory” cycle (stimulated or no) (n = 9500); those from frozen embryo transfer with hormone replacement therapy (n = 10,373); and conventional fee transfers (n = 48,152).
The results showed a higher rate of preeclampsia with frozen embryos transferred to the artificial frozen cycle (i.e. prepared with hormone therapy) (5.3%) than in an ovulatory cycle (2, 3%) or in cool cycles (2.4%). The rates were found to be equally distinct in pregnancy-induced hypertension (4.7% vs. 3.4% vs. 3.3%). These differences were statistically significant, even after adjusting for maternal characteristics (age, parity, smoking, obesity, history of diabetes, hypertension, endometriosis, polycystic ovaries, premature ovarian failure) to avoid bias.
Dr Epelboin and colleagues concluded that the study demonstrates that preparing the uterus with hormones in an artificial cycle is significantly associated with a higher risk of vascular disorders than in cycles with preserved ovulation and embryo transfers. fresh.
The use of frozen embryos has increased in IVF in recent years. The success rates of frozen-thawed embryo transfers are reported to be as successful or more successful than with fresh embryos and, since frozen transfers appear to reduce the risk of hyperstimulation, they also have safety benefits. ; the blood pressure risks seen in this and other study don’t seem to outweigh those benefits, Dr Epelboin said.
In addition, because the results obtained in an ovulatory cycle do not appear to affect the chances of pregnancy, preservation of the ovulatory cycle could be advocated as the first-line preparation in frozen embryo transfers whenever possible.
Presentation 0-182 Wednesday June 30
Higher risk of preeclampsia and pregnancy-induced hypertension with artificial cycle for transfer of frozen-thawed embryos compared to ovulatory cycle or fresh transfer after in vitro fertilization
- The corpus luteum during pregnancy
The corpus luteum is a naturally developing cluster of cells that forms in the ovary during early pregnancy and pumps out a pulse of progesterone, a fertility hormone. Progesterone supports the lining of the uterus (endometrium) during pregnancy and improves blood circulation.
- Embryo freezing and the risk of preeclampsia during pregnancy
- This is the first large-scale study to identify an association between a hormonally prepared uterus (artificial cycle) and a significantly increased risk of pre-eclampsia in pregnancy following the transfer of a frozen-thawed embryo. Several (but not all) randomized trials of freezing embryos generated from an initial collection of eggs (“freeze-all”) have observed such trends as a secondary endpoint. A substantial review of the literature published in 2018 (Maheshewari et al, Hum Reprod Update 2018) concluded that the evidence in favor of freezing embryos was ‘reassuring’ while adding ‘a need for caution’ about the increased risk of embryos. hypertension during pregnancy. Generally, embryo freezing allows multiple transfers from an initial egg collection treatment (and thus encourages single embryo transfer and avoidance of multiple pregnancies) and in total freezing protocols, avoids transfer in the same cycle in which the ovaries were stimulated.
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* When obtaining external comments, journalists are asked to ensure that their contacts are aware of the embargo on this press release.
This press release is in support of a study report by Dr Sylvie Epelboin presented online at the 37th ESHRE Annual Meeting.
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