Vitamin D binding protein correlate with estrogen increase after administration of human chorionic gonadotropin but do not affect ovulation, embryo, or pregnancy outcomes

BackgroundVitamin D binding protein (DBP) might increase substantially after ovarian stimulation and hence could be associated with IVF/ICSI outcomes because it determines the fraction of free bioavailable 25(OH) vitamin D. In this study, we aim to determine whether DBP is associated with E2 level after ovarian stimulation and IVF/ICSI outcomes.DesignPost-hoc analysis of a prospective observational cohort.SettingSingle-center study.Participants2569 women receiving embryo transfer.InterventionNone.Main outcome measuresThe main outcomes were oocyte and embryo quality as well as pregnancy outcomes.ResultsDBP concentration correlates with E2 on hCG day (=day of inducing ovulation with hCG; correlation coefficient r = 0.118, P