# Associations between breastfeeding, childhood BMI and pubertal onset: findings from a prospective cohort study

## TL;DR

This study finds that longer breastfeeding is linked to later puberty onset in children, but this effect is not explained by prepubertal BMI.

## Contribution

The study provides new evidence that breastfeeding duration is associated with delayed pubertal timing, independent of BMI.

## Key findings

- Exclusive breastfeeding for ≥3 months was linked to later age at peak velocity and maturation.
- Each additional 3 months of breastfeeding was associated with later age at take-off and peak velocity.
- Prepubertal BMI did not mediate the association between breastfeeding and pubertal timing.

## Abstract

Early onset of puberty, often characterized by an accelerated linear growth spurt, is a recognized risk factor for a range of metabolic and cardiovascular conditions. Although increased breastfeeding has been associated with later onset of puberty, the potential mediating role of prepubertal BMI in these associations remains poorly understood.

This study aimed to examine the longitudinal associations of breastfeeding duration with adolescent growth parameters, including pubertal timing, and to assess whether prepubertal BMI mediates these associations.

Adolescent growth parameters were estimated from the height growth trajectories of 613 participants (312 females and 301 males) across 6 cohorts in the Environmental Influences on Child Health Outcomes Program. These parameters were derived by fitting the Preece–Baines growth model, a parametric growth curve fitted to longitudinal height data, in participants with ≥3 height measurements spanning the whole period of growth. Linear regression models were used to examine associations of breastfeeding duration with adolescent growth parameters. Mediation analysis was conducted to explore whether prepubertal BMI mediated the association between breastfeeding and pubertal timing.

After adjusting for socioeconomic, maternal, and infant characteristics, children exclusively breastfed for ≥3 mo reached age at peak velocity and age at maturation later than those who were not exclusively breastfed [β = 0.32 y; 95% confidence interval (CI): 0.05, 0.60, and β = 0.30 y; 95% CI: 0.04, 0.56, respectively]. In adjusted models, each additional 3 mo of any breastfeeding was associated with a later age at take-off (β = 0.07 y; 95% CI: 0.00, 0.15), and later age at peak velocity (β = 0.11 y; 95% CI: 0.01, 0.20). Prepubertal BMI did not significantly mediate these associations.

Exclusive breastfeeding and longer breastfeeding duration were associated with later onset of puberty in boys and girls. Prepubertal BMI did not mediate the observed associations.