Progesterone levels during ovarian stimulation in segmented ART cycles inversely correlate with normalized birthweight of neonates conceived through subsequent frozen-thawed embryo transfer

Purpose: To evaluate the association between serum progesterone (P) at the day of ovulation trigger and neonatal birthweight in singletons born after frozen-thawed embryo transfer in segmented ART cycles. Methods: A retrospective multicenter cohort study involving data from patients who achieved uncomplicated pregnancy and term delivery of ART-conceived singleton babies following a segmented GnRH antagonist cycle. The main outcome was birthweight’s z-score of the neonate. Univariate and multivariate linear logistic regression analyses were made to investigate the relation of z-score with variables inherent to the patient and to the ovarian stimulation. The variable P per oocyte was created by dividing the value of progesterone at ovulation trigger by the number of oocytes retrieved at oocyte retrieval. Results: A total of 368 patients were included in the analysis. At univariate linear regression, the birthweight z-score of the neonate appeared to be inversely related to both P levels at the ovulation trigger (− 0.101, p = 0.015) and P levels per oocyte at trigger (− 1.417, p = 0.001), while it was directly related to the height of the mother (0.026, p = 0.002) and to the number of previous live births (0.291, p = 0.016). In multivariate analysis, both serum P (− 0.1; p = 0.015) and P per oocyte (− 1.347, p = 0.002) maintained the significant inverse association with birthweight z-score after adjusting for height and parity. Conclusions: Serum progesterone level on the day of ovulation trigger inversely correlates with normalized birthweight of neonates in segmented GnRH antagonist ART cycles.