Abstract P241: Later Menarche Onset Portends Lower Risk of Preterm Birth: Results From the Boston Birth Cohort

Introduction: Age at menarche onset reflects many health aspects in women. Later age at menarche has been associated with lower risk of several cardiometabolic disease outcomes, including diabetes and various cardiovascular diseases. However, no studies have reported the association of maternal menarche age with risk of preterm birth (PTB)—a pregnancy outcome with significant racial disparities and cardiometabolic etiology. Hypothesis: Later age at menarche onset is associated with lower risk of PTB. Methods: We conducted a case-control study in the Boston Birth Cohort, including 2242 mothers with PTB [gestational age (GA) <37 wks], and 6022 mothers with term birth (GA ≥37 wks). We used a maternal postpartum questionnaire (administered 24-72 hrs after delivery) to collect data on age at menarche, sociodemographic and lifestyle factors. We used medical records to ascertain GA. We used multivariable-adjusted logistic regression models and restricted cubic splines to examine the association between age at menarche and odds of PTB. Results: Of the 8264 mothers in our study, 46.9% identified as Black and 28.8% as Hispanic. Maternal age at delivery was 28.1y ±6.5y and age at menarche was 12.85y ±1.86y. Our multivariable-adjusted cubic spline suggested a linear dose-response association of age at menarche with odds of PTB and GA (Figure). Per 1-year later menarche onset of menarche was associated with 5% (95% CI: 2%-8%) lower odds of PTB, after adjustment for maternal place of birth, education, smoking status, Mediterranean diet score, and pre-pregnancy BMI. We found a similar pattern (5% lower odds per 1-year later, 95% CI: 1%-8%) in Black mothers. Conclusion: In a large cohort of racially and ethnically diverse women, later age at menarche is associated with lower risk for PTB. Our findings suggests that the origins of higher risk for PTB start early in life, before puberty, and appear to be independent of adiposity. Future studies are needed to identify mechanisms and points of intervention.