Maternal pre-pregnancy obesity and timing of puberty in sons and daughters: a population-based cohort study

BACKGROUND: In many countries, an increased prevalence of obesity in pregnancy has coincided with a declining pubertal age. We aimed to explore the potential effect of maternal pre-pregnancy overweight and obesity on timing of puberty in sons and daughters. METHODS: Between 2012 and 2018, 15 819 of 22 439 invited children from the Danish National Birth Cohort, born 2000–03, provided half-yearly information from the age of 11 years on the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne and axillary hair. We estimated adjusted mean monthly differences (with 95% confidence intervals) in age at attaining the pubertal milestones for children exposed to maternal pre-pregnancy obesity [body mass index (BMI) ≥30.0 kg/m(2)] or overweight (BMI 25.0 to 29.9 kg/m(2)) with normal weight (BMI 18.5 to 24.9 kg/m(2)) as reference. In mediation analysis, we explored whether childhood BMI at age 7 years mediated the associations. RESULTS: Maternal pre-pregnancy obesity was associated with earlier age at attaining most pubertal milestones in sons, and pre-pregnancy overweight and obesity were associated with earlier age at attaining all pubertal milestones in daughters. When combining all pubertal milestones, pre-pregnancy obesity [sons: −1.5 (−2.5, −0.4) months; daughters: −3.2 (−4.2, −2.1) months] and overweight [daughters only: −2.6 (−3.3, −1.8) months] were associated with earlier timing of puberty. The associations in sons were completely mediated by higher childhood BMI and partly so in daughters. CONCLUSIONS: Maternal pre-pregnancy obesity appears to lower timing of puberty through childhood obesity in sons and mainly through other mechanisms in daughters.