Low risk of adverse obstetrical and perinatal outcome in pregnancies complicated by asthma: A case control study

Asthma in pregnancy have been associated with an increased risk of pregnancy complications. Our aim was to estimate incidence and describe risk factors for adverse obstetrical and perinatal outcomes in pregnant women with asthma.

Women enrolled in the Management of Asthma during Pregnancy (MAP) program were each matched with three controls (i.e. consecutive women giving birth at our obstetrical service). Asthma severity was classified according to treatment step. Data on obstetrical and perinatal outcomes were obtained from medical records. Logistic regression analysis was applied, and findings expressed as odds ratios (OR) unadjusted and adjusted (adj) for BMI, age, parity, smoking, ethnicity and marital status.

Nine-hundred-thirty-nine pregnancies in women with asthma (i.e. cases) were compared to 2.782 controls. Overall, the incidence of complications was low, although women with asthma had a statistically significant higher risk of pre-eclampsia (5% vs. 3%, OR_adj 1.60, 95% CI 1.07-2.38; p = 0.02) and small for gestational age neonates (SGA) (OR_adj 1.30, 95% CI 1.10-1.54; p < 0.01) compared to controls. Compared to mild asthma, more severe asthma was associated with a higher risk of SGA (60% vs 53%, OR_adj. 1.30, 95% CI 1.10-1.54; p < 0.01). Women with asthma exacerbation during pregnancy tended to have a higher risk of severe pre-eclampsia (OR_adj 3.33 95% CI 0.96-11.65, p = 0.06) compared to pregnancies without any exacerbations.

The overall risk of adverse obstetrical and perinatal outcomes in pregnancies complicated by asthma is low compared to non-asthmatic women. Our observations suggest that enrollment into an asthma management program has a positive impact on overall pregnancy outcome.