Asthma Exacerbation Risk in Pregnancy and Postpartum: Assessing the Impact of Gestational Diabetes Mellitus and Other Key Factors.

Background: Asthma, affecting approximately 13% of pregnancies worldwide, and gestational diabetes mellitus (GDM), present in approximately 14%, are both associated with adverse maternal and perinatal outcomes. This study aims to address a lack of current knowledge about how GDM affects asthma during pregnancy.

Objective: To determine whether GDM is associated with an increased risk of asthma exacerbations during pregnancy and the first year postpartum.

Methods: This retrospective cohort study analyzed electronic health records of pregnant patients with asthma from 2010 to 2023, excluding those with pre-existing diabetes mellitus or concurrent chronic lung diseases. Asthma exacerbations were defined by the need for an oral corticosteroid prescription. Multivariable logistic regression and zero-inflated Poisson regression were used to adjust for age, race, body mass index (BMI), prepregnancy asthma exacerbation history, and insurance status.

Results: Among 10,985 individuals, 1492 had GDM. Patients with GDM were older with higher BMIs. GDM was associated with increased asthma exacerbation risk during pregnancy (adjusted odds ratio [OR] = 1.36, 95% confidence interval [CI]: 1.10-1.67), but not postpartum. Stratified analyses of 4331 individuals with gestational blood glucose measurement showed that each doubling of blood glucose levels doubled the risk of asthma exacerbations during pregnancy (adjusted OR = 2.02, 95% CI: 1.45-2.81). Other factors associated with asthma exacerbation included prepregnancy asthma exacerbations, older age, and Medicaid coverage.

Conclusion: The association between GDM and increased risk of asthma exacerbations underscores the need for early, universal screening and effective interventions to improve blood glucose control in pregnant individuals with pre-existing asthma.