Supraphysiologic estradiol level in ovarian stimulation cycles affects the birth weight of neonatal conceived through subsequent frozen-thawed cycles: a retrospective study.

OBJECTIVE: To investigate whether supraphysiologic estradiol (E2 ) in controlled ovarian stimulation (COS) cycles affect the subsequent frozen-thawed embryo transfer (FET) in terms of the neonatal birth weight.

DESIGN: Retrospective cohort study.

SETTING: University affiliated hospital.

POPULATION: Two thousand and sixty six patients undergoing FET cycles that result in live singleton births between July 2011 and Dec 2016.

INTERVENTION(S): None.

METHODS: Multivariable linear regression and logistic regression was used to evaluate the association between peak E2 and birth weight outcomes.

MAIN OUTCOME MEASURE(S): Birth weight, z-score adjusted for gender and gestational age and incidence of small for gestational age (SGA) and low birth weight (LBW) in singleton neonates derived from FET cycles RESULT(S): Adjusted for confounding factors, both the absolute birth weight and the z-score of singletons following FET were negatively associated with peak E2 levels in COS. In comparison with the referent category (E2 ≤1500 pg/ml), the categories with E2 >3000 pg/ml had a significantly lower z-score. The difference (95% CI) in estimated marginal mean of birth weights between referent category and highest E2 (>8000 pg/ml) category was 104.57 (18.13-181.06) g. Multiple logistic regression analyses showed that the adjusted odds ratio (95% CI) for SGA and LBW in term singletons that compared patients with E2 > 3000 pg/ml to those with E2 ≤3000 pg/ml was 2.44(1.37-4.34) and 2.32(1.01-5.40), respectively.

CONCLUSION(S): Peak E2 levels in COS cycles are negatively associated with the birth weight of singletons conceived through subsequent FET cycles. This article is protected by copyright. All rights reserved.