Acute and chronic respiratory diseases in pregnancy: Associations with placental abruption

Abstract

Placental hypoxia has been speculated as the pathway leading to an association between maternal asthma during pregnancy and risk of abruption. The objective of this study is to examine the associations between acute and chronic respiratory diseases (hypoxic conditions) and abruption. A population-based retrospective cohort study was conducted to examine the associations between maternal respiratory disease (hypoxic conditions) and risk of abruption using the National Hospital Discharge Survey. The study cohort included women that delivered a singleton live birth or stillbirth (n = 37,190,632). International Classification of Diseases Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify pregnancies hospitalized for: i) acute conditions (acute upper respiratory diseases, viral/bacterial pneumonia, and acute bronchitis/bronchiolitis) and ii) chronic conditions (chronic bronchitis and asthma) and abruption. All analyses were adjusted for maternal socioeconomic, demographic and behavioral characteristics. The rate of abruption among singleton pregnancies was 1 %. The overall rate for acute respiratory conditions was 2.1 per 1,000. Acute upper respiratory diseases (RR 3.21, 95% CI 3.04, 3.40) and viral/bacterial pneumonia (RR 2.16, 95% CI 1.94, 2.40) were associated with increased risk for abruption. The rate of chronic respiratory conditions was 8.9 per 1,000. Chronic bronchitis was strongly associated with abruption (RR 31.83, 95% CI 29.57, 34.42), but the association between asthma and abruption was weak (RR 1.03, 95% CI 1.00, 1.06). When we further stratified the data by maternal race, asthma was no longer a risk factor for abruption among whites (RR 0.89, 95% CI 0.85, 0.94) but remained a significant risk factor (RR 1.48, 95% CI 1.40, 1.57) among blacks. Pregnancies complicated by acute and chronic respiratory diseases are associated with increased risk for placental abruption. Our result suggests that a pregnancy complicated by chronic bronchitis is severe enough to warrant hospitalization.