Association Between Maternal Progesterone Use and Body Weight of Offspring in the US Collaborative Perinatal Project: A Retrospective Cohort Study

INTRODUCTION: This study aimed to evaluate whether and to what extent progesterone use during pregnancy influences offspring's body weight in a large sample, drawn from 1959 to 1976. METHODS: We used the data from the National Collaborative Perinatal Project, which retrospectively collected information on maternal progesterone use and offspring weight from birth to 7 years of age. Multivariable linear regression models were used to evaluate the association between maternal progesterone use and offspring weight, and to verify whether early pregnancy progesterone use, total duration of pregnancy, and duration of pregnancy use affect offspring weight. RESULTS: Among 49,507 mothers, 952 (1.92%) used progesterone during pregnancy. Birth weight of those who used progesterone was significantly lower than that of nonusers after adjusting for potential confounders. We found that the weight gaps were -135 g (95% CI: -163 to -106 g) at birth and -92.6 g (95% CI: -149 to -35.7 g) at 4 months. When progesterone use was first initiated in the second or third trimester, lower weight in offspring of users could persist to 8 months and 1 year, respectively. If the total duration of progesterone use during the entire pregnancy was longer than 20 days, the weight gap between offspring of users and those of nonusers could last for 1 year after birth. CONCLUSIONS: Maternal progesterone use during pregnancy might be associated with lower birth weight of offspring in this population from 1959 to 1976, which suggests that further, updated research to in other populations is warranted.