Risk factors associated with pre-eclampsia in pregnancies conceived by ART

What are the factors associated with the increased incidence of pre-eclampsia in pregnancies conceived through IVF using autologous oocytes? A nested case–control study from the combined cohort of three multicentre randomized trials comparing fresh to frozen embryo transfer, including women who achieved clinical pregnancy after the first embryo transfer. Multivariable logistic regression was used to assess the effect of baseline characteristics, ovarian response parameters, type of fertilization, type of embryo transfer, and number of gestational sacs on the risk of pre-eclampsia. There were 2965 clinical pregnancies and 90 women were diagnosed with pre-eclampsia. Twin gestations (odds ratio [OR] 2.34, 95% confidence interval [CI] 1.50–3.66), mean arterial pressure (OR 1.04, 95% CI 1.01–1.07), frozen embryo transfer (OR 2.06, 95% CI 1.27–3.35), body mass index (BMI) (OR 1.10, 95% CI 1.02–1.18), progesterone level on the day of human chorionic gonadotrophin trigger (OR 1.53, 95% CI 1.07–2.20), and the total dose of gonadotrophin (OR 0.999, 95% CI 0.999–1.000, P = 0.037) were associated with the risk of pre-eclampsia. When the analysis was confined to women who underwent frozen embryo transfer, twin gestations (OR 2.44, 95% CI 1.43–4.18), BMI (OR 1.13, 95% CI 1.03–1.23) and the total dose of gonadotrophin (OR 0.999, 95% CI 0.999–1.000, P = 0.014) were still related to the risk of pre-eclampsia. The embryo stage at transfer was not included in the final models. Frozen embryo transfer was an independent risk factor of pre-eclampsia in assisted reproductive technology. The high ovarian response may also increase the risk of pre-eclampsia. The embryo stage at transfer was not related to the risk of pre-eclampsia.