Background: The role of intergenerational influences on age at menarche has not been explored far beyond the association between mothers' and daughters' menarcheal ages. Small size at birth and childhood obesity have been associated with younger age at menarche, but the influence of maternal overweight or obesity on daughters' age at menarche has not been thoroughly examined.
Methods: In a follow-up study of the prospective Collaborative Perinatal Project, grown daughters were asked in 1987-1991 for their age at menarche. Data from the original Collaborative Perinatal Project (1959-1966) included their mothers' height and prepregnancy weight. In the follow-up study, 597 of 627 daughters had complete menarche and maternal data available and were included in the present analysis. We used polytomous logistic regression to examine the association between maternal overweight (body mass index [BMI] = 25-29.9 km/m) or obesity (BMI >or= 30) and daughter's age at menarche (<or=12, 12, 13, 14+ years).
Results: Compared with those whose mothers had a BMI less than 25, daughters of obese mothers experienced younger age at menarche (OR for menarche at <or=12 years = 3.1 [1.1-9.2]). This association remained after adjusting for maternal age at menarche, maternal parity, socioeconomic status, race, and study site (OR = 3.3 [1.1-10.0]). Effect estimates for maternal overweight were close to the null. There was limited evidence of mediation by small for gestational age or BMI at age 7.
Conclusions: Maternal obesity is associated with younger menarcheal age among daughters in this study, possibly via unmeasured shared factors.