Researchers from the Universities of Bristol and Cardiff, in the United Kingdom, studied whether there was a relationship between birth weight and lung function later in life. The investigators were specifically interested in the impact of lower birth weight in term infants on subsequent lung development. Participants were children whose mothers from the UK had been enrolled in the Avon Longitudinal Study of Parents and Children during pregnancy. This analysis included only white, singleton infants who were born at term. Participants had spirometry at age 8–9 years and/or 14–17 years. Study outcomes included forced expiratory volume in 1 second (FEV1 ), forced vital capacity (FVC), and forced mid-expiratory flow between 25% and 75% of FVC (FEF25–75). The main exposures of interest were birth weight and intrauterine growth retardation (IUGR). A child was considered to have IUGR if birth weight was <10th percentile. IUGR was further classified as “symmetric” if birth head circumference was also <10th percentile, and “asymmetric” if head circumference was ≥20th percentile. Maternal smoking during pregnancy and social class based on father’s occupation were added as possible confounders. The investigators used linear regression to assess relationships between lung function at 8–9 years of age or at 14–17 years of age, and birth weight after adjustment for gestation and sex as well as other confounders. Regression models were also constructed to determine if symmetric or asymmetric IUGR had differential effects on lung function.
Among an initial cohort of 14,062 eligible infants, 4,086 children aged 8–9 years and 2,582 adolescents aged 14–17 years had spirometry data; 2,166 had measurements at both ages. In the adjusted models, researchers found a significant association between birth weight and FEV1 (P = .007) and FVC (P = .003) at ages 8–9 years, with lower lung function measurements in those with lower birth weights. These relationships did not persist in the 14–17 year group after adjusting for confounders. There were no differences in lung function as a result of birth weight between type of growth restriction (symmetric versus asymmetric).
The authors conclude that birth weight is associated with lung function during early childhood but has a lesser effect by adolescence. They suggest that potential interventions to improve lung function should be introduced early in life and in the antenatal period.
Dr Springer has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.
Originally introduced as “the Barker hypothesis” in 1986,1 the concept now called fetal origins of adult onset disease continues to grow in acceptance as more health issues appearing later in life are being linked to fetal...