2009 pandemic influenza A (H1N1) virus infection in postpartum women in California

OBJECTIVE: The objective of the study was to characterize severe illness because of the 2009 pandemic influenza A (H1N1) infection in postpartum women. STUDY DESIGN: We reviewed case reports of infected hospitalized postpartum (<= 6 months from delivery) women identified through state-wide surveillance in California. From April 23 through August 11, 2009, all hospitalizations and/or deaths were reported. After August 11, reporting was limited to cases requiring intensive care or deaths. RESULTS: From April 23 to December 31, 2009, 15 cases were reported; 11 (73%) had symptom onset within 7 days postpartum. Of 10 hospitalized cases reported through August 11, 4 required intensive care, 3 required mechanical ventilation, and 2 died. Of 5 cases requiring intensive care reported after August 11, all required mechanical ventilation and 1 died. Overall, 6 (43%) received antivirals within 48 hours of symptom onset. CONCLUSION: The 2009 H1N1 can cause severe illness in postpartum women, especially in the first week following delivery.