Objective: To examine the association between chorioamnionitis and childhood asthma based on gestational age at birth and race/ethnicity.
Design: A retrospective cohort study using the Kaiser Permanente Southern California (KPSC) Matched Perinatal records.
Setting: Kaiser Permanente Southern California, Pasadena, California.
Participants: All singleton children born in KPSC hospitals between 1991 and 2007 (N = 510 216).
Main exposure: Clinically diagnosed chorioamnionitis.
Main outcome measures: Physician-diagnosed asthma in children aged 8 years or younger.
Results: The incidence rates of asthma among preterm- and full term-born children of pregnancies complicated by chorioamnionitis were 100.7 and 39.6 per 1000 person-years, respectively (incidence rate ratio, 2.9; 95% confidence interval [CI], 2.6-3.3). Children aged 8 years or younger with asthma were more likely to be born to women who were aged 35 years or older, African American, had 13 or more years of education, had maternal asthma, used antibiotics, had chorioamnionitis during the pregnancy, and had a male child. Multivariable Cox regression analysis revealed that children born at 23 to 28, 29 to 33, and 34 to 36 weeks' gestation after pregnancies complicated by chorioamnionitis had a 1.23-fold (95% CI, 1.02-1.49), 1.51-fold (95% CI, 1.26-1.80), and 1.20-fold (95% CI, 1.03-1.47), respectively, increased risk of asthma compared with children of similar gestational age born after pregnancies not complicated by chorioamnionitis. A preterm pregnancy complicated by chorioamnionitis was associated with increased risk of asthma among white (hazard ratio [HR], 1.66; 95% CI, 1.32-2.07), African American (HR, 1.98; 95% CI, 1.60-2.44), and Hispanic (HR, 1.70; 95% CI, 1.45-2.00), but not Asian/Pacific Islander (HR, 1.15; 95% CI, 0.83-1.58) women.
Conclusion: Findings suggest that chorioamnionitis at preterm gestation is independently associated with increased risk of childhood asthma.