Objective: To examine whether feeding patterns from birth to age 6 months modify the association between birth weight and weight at 7-12 months of age.
Study design: Longitudinal mixed models were used to examine feeding trajectories across categories of birth weight and weight at 7-12 months of age in 1799 mother-infant dyads enrolled in the Infant Feeding Practices Study II. The percentage of breast milk received and the average daily formula consumption were calculated from birth to 6 months of age. Birth weights were classified as high (≥4000 g) and normal (≥2500 g and <4000 g). Weights at 7-12 months of age were categorized as high (z score >1) or normal (z score ≤1). A secondary analysis was performed using categories defined by birth weight adjusted for gestational age percentiles (>90% and 10th-90th percentile).
Results: High birth weight (HBW) infants with high weights at 7-12 months of age demonstrated a rapid decline in the percentage of breast milk feedings compared with HBW infants with normal weights at 7-12 months of age. Normal birth weight infants with high weights at 7-12 months of age received a lower percentage of breast milk and had greater absolute intakes of formula than those with normal weights at 7-12 months of age; these associations did not vary over time. Results were similar when infants were categorized by birth weight percentiles.
Conclusions: A lower proportion of breast milk feedings was associated with excess weight at 7-12 months of age in HBW infants. These findings suggest an initial target for obesity prevention programs focusing on the first 6 months after birth.
Keywords: high birth weight; infant growth; large-for-gestational age; macrosomia; normal birth weight; pediatric obesity.
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