Effect of body weight on early hormone levels in singleton pregnancies resulting in delivery after in vitro fertilization

Abstract

To evaluate which clinical characteristics influence early maternal β-human chorionic gonadotropin (hCG) and progesterone levels in invitro fertilization (IVF) pregnancies. Retrospective cohort analysis. Academic medical center. Women with a live birth after single-blastocyst embryo transfer in either a fresh or frozen cycle between 2004 and 2017, comprising 1,282 pregnancies in 1,057 patients. None. The initial human chorionic gonadotropin concentration (β-hCG1) measured a mean of 10days (range: 9-12days) after embryo transfer, the rate of increase in β-hCG concentrations, and progesterone concentration, with all analyses controlled for number of days between the embryo transfer and the β-hCG1 measurement. The clinical factor that positively influenced the β-hCG1 level in the fresh cycle was the stimulation type (antagonist cycle higher than long agonist cycle). The clinical factors that negatively influenced both fresh and frozen cycle β-hCG1 were lower embryo quality and increasing body weight. Increasing weight negatively impacted progesterone levels in both fresh and frozen cycles. A 100 lb (45.4kg) difference in weight was associated with a 34.8% reduction in β-hCG1 for both fresh and frozen cycle pregnancies. The rate of increase in β-hCG was unaffected by body weight. A 100 lb (45.4kg) difference in weight was associated with a 53.3% and a 32.8% reduction in progesterone in fresh and frozen cycles, respectively. Increasing body weight is associated with significantly lower β-hCG and progesterone concentrations in early pregnancy after blastocyst single-embryo transfer in both fresh and frozen cycles. Clinicians should consider this when evaluating these hormone levels for prognostic and diagnostic purposes.