Preterm infants of lower gestational age at birth have greater waist circumference-length ratio and ponderal index at term age than preterm infants of higher gestational ages

Objective: To assess anthropometric changes from birth to hospital discharge in infants born preterm and compare with a reference birth cohort of infants born full-term. Study design: Retrospective chart review was conducted of 501 preterm and 1423 full-term infants. We evaluated birth and hospital discharge weight, length, and waist circumference (WC). WC/length ratio (WLR), ponderal index, and body mass index (BMI) were calculated. Preterm infants were categorized into quartiles (Q1-4) based on birth weight (BW). Results: At birth mean length, WC, WLR, BMI, and ponderal index were all significantly less for preterm infants in the lowest BW quartile (Q1) than preterm infants in higher BW quartiles or full-term infants. Although their weight, length, and BMI remained significantly less at discharge, preterm infants in Q1 had a disproportionate increase in WLR and ponderal index such that at discharge their WLR and ponderal index were greater than infants in Q2-3 and comparable with infants in Q4 and full-term infants. Discharge WLR and ponderal index in Q1 were significantly higher with decreasing postmenstrual age at birth. Conclusions: Preterm infants of a lower birth postmenstrual age have disproportionate increases in WLR and ponderal index that are suggestive of increased visceral and total adiposity.