PURPOSE OF THE STUDY.
To evaluate whether those who were born prematurely were more likely to be prescribed asthma medications in young adulthood than those who were born at term.
This was a national cohort study of all singleton infants born in Sweden from 1973 through 1979 (N = 622 616) and followed to ages 25.5 to 35.0 to determine whether asthma medications were prescribed in 2005–2007.
Asthma-medication data were obtained from all outpatient and inpatient pharmacies throughout Sweden. Outcome was defined as prescription of (1) both a β2 agonist inhalant and a glucocorticoid inhalant or (2) a combination inhalant containing a β2 agonist and other drugs for obstructive airway diseases.
Young adults who were born extremely prematurely (23–27 weeks' gestation) were 2.4 times more likely to be prescribed asthma medications than those who were born at term (95% confidence interval: 1.41–4.06). No association was found between later prematurity (28–32 or 33–36 weeks' gestation) and asthma medications in young adulthood.
Extreme preterm birth (23–27 weeks' gestation) but not later preterm birth is associated with an increased risk of asthma, at least in young adulthood.
This is the first study with adequate statistical power to evaluate the risk of asthma beyond adolescence in people who were born extremely prematurely. A meta-analysis of 19 previous studies revealed an overall odds ratio of 1.07 for risk of asthma when comparing people born at gestational ages of <37 weeks to those born at ≥37 weeks (J Allergy Clin Immunol. 2006;118:823–830), but this study did not disclose specific data for extremely preterm children. One possible explanation for the findings in the Crump et al study is that preterm birth and asthma might share common genetic determinants. The results of at least 2 previous studies suggest that maternal asthma might be associated with preterm delivery (Thorax. 1995;50:525–530 and Am J Obstet Gynecol. 2001;184:90–96). Other studies reported that maternal asthma is associated with an increased risk of asthma in their children (Am J Respir Crit Care Med. 1998;157[4 pt 1]:1073–1078 and Environ Health Perspect. 2001;109:579–582).
- Copyright © 2011 by the American Academy of Pediatrics