Characteristics and Outcomes of Hospitalized Pregnant Women With Influenza, 2010 to 2019
Rachel Holstein, Fatimah S. Dawood, Alissa O’Halloran, Charisse N Cummings, Dawud Ujamaa, Pam Daily Kirley, Kimberly Yousey‐Hindes, Emily Fawcett, Maya Monroe, Sue Kim, Ruth Lynfield, Chelsea McMullen, Alison Muse, Nancy M. Bennett, Laurie M. Billing, Melissa Sutton, Ann Thomas, H. Keipp Talbot, William Schaffner, Ilene Risk, Carrie Reed, Shikha Garg
Abstract
Background: Pregnant women may be at increased risk for severe influenza-associated outcomes. Objective: To describe characteristics and outcomes of hospitalized pregnant women with influenza. Design: Repeated cross-sectional study. Setting: The population-based U.S. Influenza Hospitalization Surveillance Network during the 2010–2011 through 2018–2019 influenza seasons. Patients: Pregnant women (aged 15 to 44 years) hospitalized with laboratory-confirmed influenza identified through provider-initiated or facility-based testing practices. Measurements: Clinical characteristics, interventions, and in-hospital maternal and fetal outcomes were obtained through medical chart abstraction. Multivariable logistic regression was used to evaluate the association between influenza A subtype and severe maternal influenza-associated outcomes, including intensive care unit (ICU) admission, mechanical ventilation, extracorporeal membrane oxygenation, or in-hospital death. Results: Of 9652 women aged 15 to 44 years and hospitalized with influenza, 2690 (27.9%) were pregnant. Among the 2690 pregnant women, the median age was 28 years, 62% were in their third trimester, and 42% had at least 1 underlying condition. Overall, 32% were vaccinated against influenza and 88% received antiviral treatment. Five percent required ICU admission, 2% required mechanical ventilation, and 0.3% (n = 8) died. Pregnant women with influenza A H1N1 were more likely to have severe outcomes than those with influenza A H3N2 (adjusted risk ratio, 1.9 [95% CI, 1.3 to 2.8]). Most women (71%) were still pregnant at hospital discharge. Among 754 women who were no longer pregnant at discharge, 96% had a pregnancy resulting in live birth, and 3% experienced fetal loss. Limitation: Maternal and fetal outcomes that occurred after hospital discharge were not captured. Conclusion: Over 9 influenza seasons, one third of reproductive-aged women hospitalized with influenza were pregnant. Influenza A H1N1 was associated with more severe maternal outcomes. Pregnant women remain a high-priority target group for vaccination. Primary Funding Source: Centers for Disease Control and Prevention.