Serum estradiol levels tied to preeclampsia risk, especially after frozen embryo transfer

Key takeaways:

• After frozen embryo transfer, estradiol levels were significantly higher for women with preeclampsia vs. women without.
• Estradiol levels in early pregnancy were independent risk factors for preeclampsia.

Higher serum estradiol levels in early pregnancy were associated with increased risk for preeclampsia, particularly after frozen embryo transfer cycles, researchers reported in Frontiers in Endocrinology.

Yun-Chiao Hsieh, MD, adjunct attending physician in the department of obstetrics and gynecology at the National Taiwan University Hospital, and colleagues used a database from a university-affiliated IVF center from 2010 to 2020 to conduct a retrospective cohort study with data from 888 women who conceived after frozen embryo transfer. Researchers determined the adjusted effect of estradiol levels on preeclampsia risk.

Overall, 95 women in the study were diagnosed with preeclampsia (mean age, 36.5 years). Serum estradiol levels during the fourth (462.1 vs. 393.7 pg/mL; P = .007) and fifth (570.3 vs. 510 pg/mL; P = .005) gestational weeks were different between women with and without preeclampsia, respectively. After frozen embryo transfer, serum estradiol levels were higher during the fifth gestational week among women with preeclampsia vs. women without (607.5 vs. 545.6 pg/mL; P = .009).

In the multivariable logistic regression model, researchers noted that estradiol levels in early pregnancy were independent preeclampsia risk factors. Researchers observed increased odds of preeclampsia as estradiol level quartiles increased when adjusting for potential confounders in frozen embryo transfer cycles. Higher maternal BMI (adjusted OR = 1.13; 95% CI, 1.07-1.2), nulliparity (aOR = 2.54; 95% CI, 1.44-4.48) and estradiol levels during the fourth and fifth gestational weeks (aOR = 1.08; 95% CI, 1.01-1.16) were associated with increased odds of preeclampsia.

The ORs for preeclampsia were significantly higher in estradiol level quartiles 3 and 4 compared with quartiles 1 and 2, the researchers wrote.

“After adjusting for estradiol levels, frozen embryo transfer programmed cycles were not independently associated with the odds of preeclampsia,” the researchers wrote. “This suggests that the estradiol levels may be the true factor influencing the odds ratio of preeclampsia after frozen embryo transfer, regardless of the choice of protocol.”