Elsevier

The Journal of Pediatrics

Volume 164, Issue 2, February 2014, Pages 295-299.e1
The Journal of Pediatrics

Original Article
The Burden of Childhood Asthma and Late Preterm and Early Term Births

https://doi.org/10.1016/j.jpeds.2013.09.057Get rights and content

Objective

To evaluate the association between gestational age at birth and the risk of subsequent development of asthma.

Study design

We conducted a retrospective observational hospital-based birth case-control study in a university-based obstetrics and gynecology department in Finland. A total of 44 173 women delivering between 1989 and 2008 were linked with the social insurance register to identify asthma reimbursements for their offspring (n = 2661). Pregnancy factors were recorded during pregnancy. Infants were categorized as moderately preterm (≤32 weeks), late preterm (33-36 weeks), early term (37-38 weeks), term (39-40 weeks), or late term and postterm (≥41 weeks). The main outcome measure was asthma among the infants.

Results

Children born moderately preterm (≤32 weeks gestation) had a significantly increased risk of asthma (aOR, 3.9; 95% CI, 3.2-4.8). The risk of asthma was also increased in those born late preterm (aOR, 1.7; 95% CI, 1.4-2.0) and early term (aOR, 1.2; 95% CI, 1.1-1.4). In contrast, delivery at 41 weeks or later seemed to decrease the risk of asthma (aOR, 0.9; 95% CI, 0.8-1.0). The burden of asthma associated with preterm birth was associated mainly with early term infants, in whom 108 extra cases of asthma were observed.

Conclusion

Even though the individual risk of asthma was inversely correlated with gestational age at birth, the overall burden brought about by delivery before term was associated with late preterm and early term deliveries. Furthermore, delivery after term was protective against asthma.

Section snippets

Methods

The study population was derived from a clinical birth database comprising a total population of 45 030 infants born after 22 completed weeks of gestation at Kuopio University Hospital between 1989 and 2008 (Table I). Stillbirths (n = 193), neonatal deaths (n = 177), and cases with missing data (n = 487) were excluded. Data on 44 173 women with live-born infants were linked with data from the register for reimbursement at the Social Insurance Institution of Finland for asthma medication for

Results

Of the 44 173 live-born children, 2661 (6.0%) had asthma during childhood (Table I). The mean age of onset of asthma was 4.2 years, and more than 80% of the children with asthma were aged >7 years. Table I shows that compared with controls, children with asthma were more frequently males and were born more frequently by cesarean delivery, at a lower gestational age, with lower Apgar scores, and to married couples vs controls. Mothers of children with asthma smoked more during pregnancy and had

Discussion

The overall prevalence of childhood asthma in our study cohort was 6%, which corresponds closely to the expected rate in Finland.14 We report 3 main finding. First, the risk of asthma was 3.9-fold higher in children born at <32 weeks gestation compared with controls, and it remained high in those born at up to 38 weeks gestation. Second, delivery after 41 weeks seemed to protect offspring from asthma. Third, the burden of asthma in offspring was associated mainly with deliveries at 37-38 weeks

References (20)

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Supported by The Pohjois-Savo Hospital District EVO-funding (Awarded Special State Subsidy) for health science research. The authors declare no conflicts of interest.

Registered with Kuopio University Hospital register (TUTKI): 5302448.

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