Breastfeeding duration moderates the association between early-life risk factors and growth trajectory from birth to 2 years

Background: Optimal breastfeeding behavior tends to cluster with other behaviors that are protective against the development of obesity making it very challenging to determine its true benefit. Our objective was to determine if longer breastfeeding duration was protective against rising growth trajectories by comparing its effects in children with different risk for obesity. Methods: This study utilized longitudinal data from a birth cohort in rural upstate New York (n=595). The outcome, weight-for-length z-score trajectory from birth to 2 years, was classified using latent-class modeling, that grouped children based on similar growth trajectories. Four trajectories emerged: high-rising, low-rising, mid-stable, and low-stable. An early-life risk index for obesity, classified into 3 levels (low, medium, high), included maternal BMI category, gestational weight gain, smoking during pregnancy, maternal education, and stress at 1 year post-partum. Logistic regression analysis was performed to investigate whether breastfeeding duration (<2 months, 2-4 months, >4 months) moderated the association between early-life obesity risk and infant growth trajectory. Results: Infants at high-risk for obesity who were breastfed for <2 months were more likely to be in a rising growth trajectory (p < 0.05 for both low-rising and high-rising) compared to infants who were breastfed for longer durations. Infants at medium-risk for obesity who were breastfed for <2 months were more likely to be in the high-rising growth trajectory (P <0.01). Conclusion: Short breastfeeding duration, especially for infants at higher risk for obesity, is associated with accelerated growth from birth to 2 years.