Pregnant women who contract the H1N1 flu strain are at risk for obstetrical complications including fetal distress, premature delivery, emergency cesarean delivery and fetal death, according to a report in the May 24 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

“Novel influenza A (H1N1) is a pandemic respiratory infection commanding much attention by the international medical community,” the authors write as background information in the article. “Little data have been reported regarding the impact of H1N1 on pregnant patients or the gestational fetus, and published reports have been conflicting.” The study also notes that during prior seasonal influenza epidemics and pandemics, pregnant women have been reported to have increased hospitalization rates, increased illness and mortality, but no increase in birth defects. Historically, pregnant patients during the flu pandemics of 1918 and 1957 had high mortality rates.

“Because obstetrical patients make up a vulnerable population, it is crucial to characterize in them the severity and course of H1N1,” writes Andrew C. Miller, M.D., of the State University of New York Downstate Medical Center and Kings County Hospital Center, Brooklyn, and colleagues.

The researchers analyzed data from 18 patients, with an average age of 27, who were admitted to two urban academic medical centers with a diagnosis of H1N1 from May 18 to June 24, 2009. The results were then compared with published reports of the H1N1 outbreak and reports of flu pandemics of 1918 and 1957.

All patients were treated with oseltamivir phosphate beginning on the day of admission. Three of the 18 patients were admitted to the intensive care unit, and seven patients delivered during their hospital stay, six prematurely. Of these six premature births, five involved fetal distress and four were delivered via emergency Cesarean delivery (C-section). There were no congenital birth defects identified; however, two fetal deaths were recorded. No maternal deaths were reported.

“Little data are available regarding fetal outcomes and mortality rates among H1N1-infected mothers. Of the 18 patients in this series, one had a spontaneous abortion and one died postnatally from complications of extreme prematurity and sepsis,” the authors write.

Based on the findings of the observational study, the authors conclude that “H1N1 poses a serious health threat to pregnant patients.” The authors also conclude that fetal distress necessitating emergency Cesarean delivery may result in significant illness; however, this study showed an absence of maternal deaths as compared to prior study results. According to the authors’ conclusions, “early antiviral treatment may improve maternal outcomes.”

(Arch Intern Med. 2010;170[10]:868-873. Available pre-embargo to the media at http://www.jamamedia.org.)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

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Source:  American Medical Association (AMA)