Association of maternal and intrauterine characteristics with age at menarche in a multiethnic population in Hawaii

This study seeks to further elucidate the mother–daughter hormonal relationship and its effects on daughter’s breast cancer risk through the association with early age at menarche. Four hundred and thirty-eight healthy girls, age 9–18 and of White, Asian, and/or Polynesian race/ethnicity, were recruited from an HMO on Oahu, Hawaii. Anthropometric measures were taken at a clinic visit, and family background questionnaires were completed. Cox proportional hazards regression was used to test the association of maternal and intrauterine hormone-related exposures with age at menarche. Weight and gestational age at birth and maternal pregnancy-induced nausea were not associated with age at menarche. Each year older of the mother’s age at menarche was associated with a 21% reduced risk of an early age at menarche for the daughter (95% CI: 0.73–0.86). This association between mother’s and daughter’s menarcheal age was statistically significant for girls of Asian, White, and Mixed, Asian/White race/ethnicity, but not for girls of Mixed, part-Polynesian race/ethnicity (p _interaction = 0.01). There was a suggestion that maternal history of breast cancer was associated with an increased risk of early age at menarche (HR = 2.18, 95% CI: 0.95–4.98); there was no association with second-degree family history. These findings support the hypothesis that maternal and intrauterine hormone-related exposures are associated with age at menarche.