Hospitalizations with respiratory illness among pregnant women during influenza season.

OBJECTIVE To examine hospitalizations with respiratory illness among pregnant women in the United States during periods of influenza activity. METHODS Data were obtained from the Healthcare Cost and Utilization Project National Inpatient Sample (NIS), the largest publicly available all-payer hospital discharge database. Hospitalizations for respiratory illness and pregnancy were classified with International Classification of Diseases, 9th Revision, Clinical Modification codes. Analyses were stratified by delivery status. Discharge characteristics, length of stay, and complications of delivery among hospitalized pregnant women with and those without respiratory illness were compared. RESULTS During the 1998-2002 influenza seasons, 3.4 per 1,000 hospitalizations of pregnant women included diagnoses of respiratory illness. Characteristics of pregnancy hospitalizations associated with higher odds of respiratory illness were presence of a high-risk condition for which influenza vaccination is recommended (adjusted odds ratio [OR] 3.2, 95% confidence interval [CI] 3.0-3.5 and OR 6.0, 95% CI 5.2-6.9 for nondelivery and delivery, respectively), Medicaid/Medicare as primary expected payer of care (OR 1.2, 95% CI 1.1-1.3 and OR 1.9, 95% CI 1.7-2.2 for nondelivery and delivery, respectively), and hospitalization in a rural area (OR 1.2, 95% CI 1.1-1.4 for nondelivery). During influenza season, hospitalized pregnant women with respiratory illness had significantly longer lengths of stay and higher odds of delivery complications than hospitalized pregnant women without respiratory illness. CONCLUSION Hospitalizations with respiratory illness among pregnant women during influenza season are associated with increased burden for patients and the health care system. Intervention efforts to decrease influenza-related respiratory morbidity among pregnant women should be encouraged. LEVEL OF EVIDENCE III.