Maternal body composition and gestational weight gain in relation to asthma control during pregnancy

Background Poor asthma control is common during pregnancy and contributes to adverse pregnancy outcomes. Identification of risk factors for poor gestational asthma control is crucial. Objective Examine associations of body composition and gestational weight gain with asthma control in a prospective pregnancy cohort (n = 299). Methods Exposures included pre-pregnancy body mass index (BMI), first trimester skinfolds, and trimester-specific gestational weight gain. Outcomes included percent predicted forced expiratory volumes (FEV1, FEV6), forced vital capacity (FVC), peak expiratory flow (PEF), FEV1/FVC, symptoms (activity limitation, nighttime symptoms, inhaler use, and respiratory symptoms), and exacerbations (asthma attacks, medical encounters). Linear and Poisson models examined associations with lung function (β (95% confidence interval (CI)), asthma symptom burden (relative rate ratio (RR (95%CI)), and exacerbations (RR (95%CI)). Results Women with a BMI ≥ 30 had lower percent predicted FVC across pregnancy (β_{ThirdTrimester}: -5.20 (-8.61, -1.78)) and more frequent night symptoms in the first trimester (RR: 1.66 (1.08, 2.56)). Higher first trimester skinfolds were associated with lower FEV1, FEV6, and FVC, and more frequent night symptoms and inhaler use across pregnancy. Excessive first trimester gestational weight gain was associated with more frequent activity limitation in the first trimester (RR: 3.36 (1.15, 9.80)) and inhaler use across pregnancy (RR_{ThirdTrimester}: 3.49 (1.21, 10.02)).