Low-Normal Gestational Age as a Predictor of Asthma at 6 Years of Age

Abstract

Background. Perinatal factors, including gestational age and birth weight, influence the development of atopy in early life. However, the role of these factors in the development of asthma in later life among children who do not develop perinatal respiratory disease remains unclear. Methods. Four hundred fifty-four infants who had a history of allergy or asthma in at least 1 parent, were born in the 36th week of gestation or later, and did not develop perinatal respiratory distress were monitored for at least 6 years. Associations between predictor variables and asthma and wheeze were assessed with multivariate logistic regression and repeated-event analyses. Results. Although we previously observed a relationship between low birth weight and persistent wheeze in the first 1 year of life, we did not observe similar associations between low birth weight and asthma at 6 years of age (odds ratio [OR]: 1.05; 95% confidence interval [CI]: 0.40–2.73). However, a strong relationship was found between low-normal gestational age and asthma at 6 years of age (OR: 4.7; 95% CI: 2.1–10.5). The effects of low-normal gestational age were significantly greater among boys than among girls (boys: OR: 8.15; 95% CI: 2.98–22.3; girls: OR: 1.90; 95% CI: 0.38–13.83). Longitudinal analysis of the relationship between gestational age and wheeze during the 6 years of observation confirmed these gender differences. Conclusions. Among children at high risk of developing atopic disease, late prematurity might be an important additional determinant of asthma later in life, and these effects are gender specific.