Breastfeeding and infant growth in relation to childhood overweight - a longitudinal cohort study.

BACKGROUND

Rapid infant growth is positively, and breastfeeding inversely, associated with childhood overweight. However, the interplay has only been sparsely investigated.

OBJECTIVES

We aimed to investigate how exclusive breastfeeding duration modifies the effect of infant growth on childhood overweight.

METHODS

We included routinely collected data on duration of exclusive breastfeeding and child growth from Aarhus Municipality, Denmark and on maternal health from the patient records at Aarhus University Hospital, 2008-2013. Infant growth was estimated using latent class analysis. Duration of exclusive breastfeeding was grouped as never, ≤4 mo, and >4 mo. Childhood overweight was defined as a body mass index z-score >1 at age 5 to 9 y. We investigated the risk of overweight dependent on infant growth and breastfeeding duration both independently and combined using logistic regression and adjusting for potential confounders.

RESULTS

Among 7074 infants, we identified 3 growth patterns: average, accelerated, and decelerated. No or ≤4 mo of breastfeeding was associated with being overweight at 5 to 9 y (adjusted odds ratio [aOR]: 1.61; 95% confidence interval [CI]: 1.27, 2.03 and aOR: 1.54; 95% CI: 1.28, 1.85, respectively) compared to >4 mo of breastfeeding. Compared with average infant growth, accelerated growth was associated with childhood overweight (aOR: 1.35; 95% CI: 1.01, 1.79). In the combined analysis, accelerated infant growth showed no evidence of being associated with overweight if infants were exclusively breastfed >4 mo (aOR: 1.20; 95% CI: 0.68, 2.10). Decelerated growth was not associated with overweight regardless of exclusive breastfeeding duration, compared with infants with average growth who were exclusively breastfed >4 mo.

CONCLUSIONS

Longer duration of exclusive breastfeeding was associated with decreased risk of being overweight, whereas accelerated infant growth was associated with increased risk. Children with accelerated infant growth who were never breastfed had the highest risk of being overweight at 5 to 9 y of age, whereas there was no association if infants were exclusively breastfed >4 mo.