Early-Life Weight Status and Risk of Childhood Asthma or Recurrent Wheeze in Preterm and Term Offspring

The purpose of the study was to determine if there was a correlation between weight-for-age (WFA) of preterm and term infants and the development of recurrent wheeze and or asthma by age 3 and 6 years.The data were obtained from 804 children whose mothers were participants in a placebo-controlled, double-blind trial of pregnant women ages 18 to 39 years who were either given placebo or Vitamin D starting at 10 to 18 weeks gestation. The women either had personal or family history of atopy and could not have chronic medical conditions, multiple gestations, or major fetal anomalies. The offspring of these women were followed at 3 and 6 years of age to determine if they had developed recurrent wheeze or asthma.Birth weight and gestational age were collected from labor and delivery forms. Preterm birth was defined as less than 37 weeks and term pregnancy as at least 37 weeks gestation. Measurements for weight were obtained at subsequent annual in-person visits. The World Health Organizations growth standards were used as references to determine the WFA z score, which compared the participants weight with the average weight of comparable children.Overall, 8.8% of the infants were born premature. The offspring’s WFA z scores showed a positive correlation with BMI z scores throughout early life. In a stratified analysis, term offspring showed an increase in the odds of asthma or recurrent wheeze by age 3 and 6 years of 22% and 15%, respectively. However, for preterm offspring, by age 3, the odds of having either asthma or recurrent wheeze showed a negative correlation with increase in weight, decreasing by 10% for each unit increase in WFA z score, and risk decreased by 27% by age 6 years.Higher WFA z scores were associated with increased odds of asthma or recurrent wheeze by age 3 and 6 years in term infants, but they were associated with lower risk of asthma or recurrent wheeze in preterm infants (representing catch-up growth). Appropriate weight gain in preterm and term infants at high risk of asthma may help to decrease the odds of developing asthma later in childhood.It is well understood that there are many factors that can influence a child’s risk of developing asthma, and this study indicates that early life weight is among those factors. This study of infants at high risk of asthma showed that an increasing WFA was a risk for asthma or recurrent wheeze, but this finding was driven primarily by the term infants. Preterm babies often struggle with appropriate weight gain, and this study demonstrates that those born preterm that are able to catch up, have a lower risk of developing asthma. Taken together, the study indicates the importance of ensuring appropriate weight gain for term and preterm infants where the goals may differ.