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 statewide 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.
Since its emergence in April 2009, the 2009 pandemic influenza A (H1N1) virus (2009 H1N1) has spread rapidly throughout the world. As seen in previous pandemics and with seasonal influenza, pregnant women are at high risk for severe complications from the 2009 H1N1 infection, with reports describing an approximately 4-fold higher rate of hospitalization compared with the general population.
Pregnant women also account for a disproportionate number of deaths from the 2009 H1N1: 5% of deaths because of the 2009 H1N1 in the United States were among pregnant women, whereas pregnant women make up only about 1% of the population. In a previous report from California, we also found an increased risk for severe disease, with 18 of 94 hospitalized pregnant women requiring intensive care (19%) and 6 dying.
The risk associated with seasonal influenza, or 2009 H1N1, in the postpartum period has not been well studied. Given that the postpartum period is a time of return to nonpregnant physiology, an increased risk during this time period might be expected, but the magnitude of the risk and how long it extends beyond delivery are unknown. Limited data suggest that women with symptom onset in the postpartum period might be at increased risk for the 2009 H1N1-associated complications.
In our previous report based on California surveillance data reported from April 23 through Aug. 11, 2009, 8 women with the onset of symptoms because of the 2009 H1N1 in the first 2 weeks postpartum were hospitalized; of these, 4 required intensive care and 2 died. However, given that we restricted the postpartum period to the first 2 weeks following delivery in that analysis, we were unable to examine whether the time period of increased risk extended further postpartum. In a report from South Africa, 2 deaths were reported among women in the first 6 weeks postpartum, but further information on the timing of symptom onset was not provided.
To better understand the experience during the postpartum period, we provide a detailed description of the clinical course and characteristics of 15 women with onset of symptoms of influenza in the first 6 months following delivery hospitalized with the 2009 H1N1 who were reported to the California Department of Public Health (CDPH) from April 23 to Dec. 31, 2009.
Materials and Methods
Beginning in April 2009, the 2009 H1N1 influenza was made a reportable disease in California. CDPH and 61 local health departments initiated an additional enhanced surveillance for hospitalized and fatal cases of the 2009 H1N1. A case was defined as a person who was hospitalized for at least 24 hours with influenza-like symptoms and had laboratory results by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) indicative of the 2009 H1N1 infection, including cases classified as probable (defined as detection of influenza A by rRT-PCR that is nonsubtypeable for human subtypes H1 or H3) or positive by specific PCR for 2009 H1N1. A fatal case was defined as a death with rRT-PCR–confirmed 2009 H1N1 listed as a contributing or underlying cause in a person with influenza-like symptoms.
Providers and hospitals were asked to report all hospitalized and fatal cases of the 2009 H1N1 to local health departments, using a standardized case history form with demographic, clinical, laboratory, and radiographic data. Additional medical chart review and abstractions were performed by staff at the local health department or CDPH. Laboratory testing by rRT-PCR for the 2009 H1N1 infection was conducted at local public health laboratories, the CDPH Viral and Rickettsial Disease Laboratory, the Centers for Disease Control and Prevention (CDC) Virus Surveillance and Diagnostic Branch Laboratory, Influenza Division, or at a commercial laboratory.
From April 23 through Aug. 11, 2009, all hospitalizations and/or deaths because of the 2009 H1N1 were reported to the CDPH. From Aug. 12 to Dec. 31, 2009, reporting was limited to cases who were admitted to intensive care units (ICUs). Postpartum cases were defined as those with the onset of influenza symptoms in the 6 months following delivery to better define the time of actual risk and were identified either by answering a specific question about postpartum status on the case report form or by review of the medical record.
Other key variables collected included maternal age and race/ethnicity, influenza signs and symptoms, date of symptom onset, use and timing of antiviral medications, diagnosis of pneumonia, ICU admission, mechanical ventilation of the patient, and any underlying medical conditions or previous pregnancy complications. We included 8 previously reported cases in our analysis, with the goal of providing a more inclusive clinical summary of all infected postpartum cases identified within 6 months following delivery reported to date. Descriptive analysis of these demographic and clinical characteristics was performed using SAS version 9.2 (SAS Institute, Cary, NC).
This activity was reviewed by the California Committee for the Protection of Human Subjects and determined to be a public health response that did not require institutional review board approval.
Results
From April 23 through Dec. 31, 2009, 15 postpartum women hospitalized with the 2009 H1N1 were reported (8 of these had been previously reported elsewhere ). Dates of symptom onset ranged from June 12 to Oct. 24, 2009. The median age was 26 years (range, 19–41 years). Eleven cases (73%) had onset of symptoms within 7 days postpartum ( Figure ). For all cases the median time from admission to the hospital for delivery to onset of symptoms postpartum was 4 days (range, 1–90). Three cases reported exposure to ill contacts at home in the 7 days prior to symptom onset.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
