Smoking and alcohol use during pregnancy and age of menarche in daughters.

Background: We assessed whether exposure to prenatal smoking or alcohol accelerates age of menarche (AOM) in offspring.
Methods: We studied a Danish cohort of 3169 singleton females born in April 1984-April 1987. Linear regressions were conducted to examine associations between prenatal smoking or alcohol exposure and offspring's AOM on: (i) the daughters who provided data on both month and the year of menarche (n= 1634) and (ii) the entire sample that provided at least the year of menarche (n= 3169). We also examined associations between only pre-pregnancy smoking or childhood exposure to smoking and AOM. The full model was adjusted for maternal pre-pregnancy body mass index, maternal age at childbirth, parental socio-economic status, parity, consumption of milk products during pregnancy and marital status.
Results: Among those who provided both year and month, AOM was accelerated by 2.8 months (95% CI in months: -5.3, -0.4) among those exposed to 10+ cigarettes/day throughout pregnancy and by 4.1 months (95% CI in months: -7.7, -0.5) among those with mothers who quit smoking sometime during pregnancy, compared with the unexposed group after adjustment for covariates. Similar, but much weaker, associations were observed among girls whose mothers smoked 1-9 cigarettes/day throughout pregnancy or whose fathers smoked compared with their unexposed counterparts after adjustment for covariates [-0.8 months (95% CI: -2.6, 1.0)]. No associations were observed between AOM and only pre-pregnancy smoking or only childhood exposure or prenatal alcohol exposure.
Conclusions: Our study indicates that heavy smoking throughout the pregnancy may be important in prenatal programming of AOM.