Pregnancies resulting from frozen-thawed embryos have an increased risk of pre-eclampsia and hypertension, according to a sizable study from France that was presented at the European Society of Human Reproduction and Embryology's online annual meeting last year.
The researchers said in their report that the results are "in keeping with past population-level studies" demonstrating a greater risk of hypertensive problems during pregnancy following frozen embryo transfer.
Some IVF clinicians wonder if the relationship between fresh vs. frozen embryo transfers and high blood pressure concerns is actually due to fresh vs. frozen embryo transfers, but the new study did not assess this possibility.
"There is one issue that is unclear: did the methodology utilised cause it, or did the actual process of freezing the embryo? According to current research and data, the majority of IVF specialists think the pharmaceutical regimen, not the IVF process, is to blame, according to Dr. Aimee Eyvazzadeh, a reproductive endocrinologist in San Francisco who was not involved in the new study. She wrote in an email to CNN on Monday.
A uterus can be prepared for transfer in a variety of ways, she explained. A corpus luteum cyst, a fluid-filled mass that develops in the ovaries and is vital during pregnancy because it generates the hormone progesterone, which is required throughout pregnancy, is included in one protocol. Another procedure uses drugs to simulate ovulation.
Studies demonstrate that the absence of the corpus luteum raises the risk, which may explain why a frozen transfer may have a higher risk of pre-eclampsia.
Overall, she added, "anyone caring for pregnant patients following IVF" should take note of the new findings. "Anyone caring for women who become pregnant following IVF must keep a close eye to this study. IVF specialists already know that IVF following a frozen embryo transfer might raise pre-eclampsia risk, and more and more research are confirming this.
