Perinatal Outcomes Associated with Maternal Asthma and Its Severity and Control During Pregnancy

Estimates of the effects of maternal asthma on pregnancy outcomes are inconsistent across studies, possibly because of differences in exposure definition.

To evaluate the risk of adverse perinatal outcomes associated with maternal asthma diagnosis, severity, and control in a large, nationally representative cohort.

This study was conducted within the IBM Health MarketScan Commercial Claims and Encounters Database (2011-2015) and the Medicaid Analytic eXtract database (2000-2014). Asthma was identified by diagnosis and treatment codes, severity was based on medications dispensed, and control was based on short-acting β-agonist dispensations and exacerbations. We estimated the relative risks (RRs) of stillbirth, spontaneous abortion, preterm birth, small for gestational age (SGA), neonatal intensive care unit (NICU) admission, and congenital malformations, comparing pregnancies with differing asthma disease status.

We identified 29,882 pregnancies complicated by asthma in the MarketScan database and 160,638 in the Medicaid Analytic eXtract database. We observed no consistent associations between asthma diagnosis, severity, or control, and stillbirth, abortions, or malformations. However, we observed increased risks of prematurity, SGA, and NICU admission among women with asthma compared with those without asthma. Compared with women with well-controlled asthma, women with poor control late in pregnancy had an increased risk of preterm birth (relative risk, 1.39; 95% CI, 1.32-1.46) and NICU admission (relative risk, 1.26; 95% CI, 1.17-1.35). More severe asthma was associated with SGA (relative risk, 1.18; 95% CI, 1.07-1.30).

We did not observe an increased risk of pregnancy losses or malformations among women with asthma. However, we found an association between asthma severity and SGA, and between exacerbations late in pregnancy and preterm delivery and NICU admission.