942: How much is too much? Adverse pregnancy outcomes associated with estradiol level at embryo transfer

Abstract

To delineate the relationship between estradiol level at the time of embryo transfer and the development of obstetric complications. This study is a retrospective cohort of 99 patients who underwent IVF, with delivery of a singleton greater than 24 weeks at a single institution from 2012-2018. Data were analyzed in relation to the patient’s cycle type, fresh (n=54) v frozen (n=45) embryo transfer, and the estradiol level at the time of transfer. The primary outcome was placental-related composite morbidity (abnormal placentation, hypertension, gestational diabetes, oligohydramnios, and SGA). There was a significantly higher composite morbidity in the fresh, compared to the frozen group (69% v 44%, p=0.01). Neonates in the fresh group were 194g smaller, and significantly more likely to be SGA (15% v 2%, p=0.02). There was a higher frequency of LGA neonates in the frozen group (18% v 6%, p=0.05), despite a similar rate of diabetes. Estradiol levels were significantly higher in the fresh versus frozen group (524 v 2640pg/mL, p< 0.001). When assessed by low, medium, and high categories of estradiol level, a parabolic relationship was observed, such that the highest rate of complications occurred in the medium group. One potential explanation for the disparity in adverse outcomes is hyperestrogenic-induced vascular remodeling resulting from ovarian stimulation in the fresh group. We sought to elucidate the relationship between placental-related morbidity and estradiol level at the time of transfer. The highest frequency of adverse outcomes was noted in the medium group (estradiol 750-2000pg/mL), demonstrating a parabolic relationship in which lower frequencies were noted in the low and high categories. This likely represent a dose-dependent response which reaches saturation of estrogen receptor signaling, with down-regulation of the receptor at higher estrogen concentrations. These results provide further evidence for the benefit of frozen embryo transfer, and may help to stratify which patients may benefit from frozen cycle transfer based on estradiol level.View Large Image Figure ViewerDownload Hi-res image Download (PPT)