Estradiol level at time of ovulatory trigger is not associated with increased odds of hypertensive disorders of pregnancy or small-for-gestational age in fresh embryo transfer cycles

Supraphysiologic estradiol levels at the time of fresh embryo transfer (ET) have been implicated in abnormal early placental development. We sought to determine if serum estradiol level at the time of ovulatory trigger is predictive of hypertensive disorders of pregnancy (HDP) and small-for-gestational age (SGA) in fresh ET cycles. Retrospective cohort study of women with singleton pregnancies who underwent fresh ET with hCG or hCG with GnRH agonist trigger and had a live birth >20 weeks at a single institution from 2013-2019. The primary outcome was HDP during the delivery hospitalization. The secondary outcome was SGA. We performed multivariable logistic regression analyses to determine if the estradiol level at the time of trigger predicts HDP and SGA, controlling for age, pre-pregnancy BMI, and maternal comorbidities (diabetes, hypertension, antiphospholipid antibody syndrome, or lupus). We included 589 women who conceived via fresh ET. The median estradiol level for the cohort was 1,748 IU/L (IQR: 1200, 2429) and 71.0% received an hCG-only ovulatory trigger. Prevalence rates were 13.6% for HDP and 14.4% for SGA. Multivariable regression analysis did not demonstrate an association between the estradiol level at the time of ovulatory trigger and HDP (aOR: 0.99, 95% CI: 0.96-1.01). Similarly, the estradiol level at the time of ovulatory trigger was not associated with a diagnosis of SGA (aOR: 1.02, 95% CI: 1.00-1.05). Estradiol level at time of trigger is not associated with hypertensive disorders of pregnancy or small-for-gestational age in women delivering singleton pregnancies following fresh embryo transfer.