Human Milk Feeding Practices and Pubertal Timing: Insights from the Generation XXI Population-Based Birth Cohort

Evidence regarding the potential influence of human milk feeding on pubertal timing remains inconsistent.

This study explored the association between human milk feeding (never, nonexclusive, or exclusive) and its duration with pubertal timing, using longitudinal data from a population-based birth cohort.

The sample included 4745 children from the population-based Portuguese birth cohort Generation XXI, with data on human milk feeding, feeding duration, and Tanner stages at 10 years of age. A Puberty score was derived from Tanner stages (range: 2-10). Human milk feeding was categorized according to exclusivity and duration (never; nonexclusive; exclusive < 4 mo; and exclusive ≥ 4 mo). Multinomial logistic regression and Cox proportional hazard models were used to estimate the association between human milk feeding categories and both puberty score and age at menarche, adjusting for maternal and child characteristics.

After adjustment for confounders, females who received human milk had lower odds ratio (OR) of a higher puberty score at 10 y of age (exclusive ≥4 mo-OR: 0.33; 95% CI: 0.24, 0.47) than those never fed human milk. Exclusive human milk feeding was associated with later age at menarche. No significant associations were found in males, except that those receiving "any but never exclusive" human milk feeding, who had lower OR of being in the highest puberty score (≥5; OR: 0.48; 95% CI: 0.25, 0.94).

These findings suggest that human milk feeding, particularly exclusive human milk feeding for ≥4 mo, may be associated with later pubertal timing among females.