Growth trajectories of extremely low birth weight infants from birth to young adulthood: a longitudinal, population-based study

Abstract

We compared sex-specific growth attainment of a population-based cohort of 147/166 (89%) extremely low birthweight (ELBW < 1000 g) and 131/145 (90%) sociodemographically comparable normal birthweight (NBW) cohort at young adulthood, and examined the pattern of growth trajectories and correlates of growth at ages 1, 2, 3, and 8 y, and teen and young adulthood (mean age, 23.3 versus 23.6 y). The proportion considered small for gestational age was ELBW 25% versus NBW 3%; and 26% versus 2% had neurosensory impairments. Weight for age z-scores for ELBW showed substantial decline to age 3 y, with subsequent significant catch-up to adolescence and smaller gains to adulthood. Height for age z-scores showed both sexes of ELBW were disadvantaged at every age compared with NBW and their expected mid-parental height. The BMI z-scores for ELBW showed a sustained incline from age 3 to adulthood, where both sexes normalized to above zero, and were comparable to their peers. ELBW children showed growth failure during infancy, followed by accelerated weight gain and crossing of BMI percentiles at adolescence, a pattern that may increase the risk of insulin resistance and coronary heart disease. However, normalization of BMI for both sexes at adulthood suggests that final growth was proportionate.