Early-life determinants of excess weight in children born heavy.

Infants born heavy are vulnerable to later obesity, but it is unknown whether obesity-related risk factors present between conception and delivery predict their postnatal weight trajectory. We modelled the weight trajectories of infants born high birth weight (HBW, greater than or equal to 4000 g) and/or large for gestational age (LGA, greater than 90th percentile) using data from the Infant Feeding Practices Study II (N = 371). A high percentage of infants were both HBW and LGA, but the trajectories were modelled separately. Weight of infants born heavy begins high, gradually decreases, and then levels off by 12 months. Delivery method was the only predictor of weight. Caesarean-delivered HBW infants were heavier than vaginally-delivered HBW infants although this effect disappeared by 12 months. Findings indicate that early-life influences are not necessarily deterministic of the postnatal weight trajectory of infants born heavy. Future research is needed to examine postnatal behaviours that may be implicated in the relationship between large size at birth and later obesity.