BACKGROUND: Assessment of asthma control every 4-6 weeks during pregnancy is recommended to reduce risk of exacerbation, and by that improve outcome.

OBJECTIVE: To identify determinants of pregnancies with low risk of asthma exacerbation.

METHODS: All pregnant women enrolled into the Management of Asthma during Pregnancy (MAP) programme at Hvidovre Hospital since 2007. Assessment of asthma control, adjustment of treatment, spirometry and measurement of exhaled nitric oxide (FENO) were performed, and baseline characteristics and exacerbation history were collected at enrolment. Determinants of low-exacerbation risk pregnancies were identified by logistic regression analysis (stepwise backward elimination).

RESULTS: In 1283 pregnancies, 107 exacerbations were observed. Multiple regression analysis revealed that no history of pre-pregnancy exacerbations (P < .001), no prescribed controller medication (P < .001), and clinically stable asthma at enrolment (P = .002) were significantly associated with low risk of exacerbation during pregnancy; with these combined characteristics, only two of 385 pregnancies were complicated by an exacerbation (OR 0.04, 95% CI 0.01-0.18, P < .001).

CONCLUSION AND CLINICAL RELEVANCE: Clinically stable asthma at enrolment, together with no history of previous exacerbations and no prescribed controller medication, is a determinant of low risk of an asthma exacerbation during pregnancy, which may guide clinicians in individualizing surveillance of asthma during pregnancy.