Skip Navigation U.S. Department of Health and Human Services
Agency for Healthcare Research Quality
Archive print banner

Outcomes/Effectiveness Research

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: Let us know the nature of the problem, the Web address of what you want, and your contact information.

Please go to for current information.

Researchers find no adverse perinatal outcomes associated with respiratory hospitalizations of pregnant women during flu season

Since 1998, the American College of Obstetricians and Gynecologists and the Centers for Disease Control and Prevention have recommended influenza vaccination for all pregnant women who will be in the second or third trimester of pregnancy during flu season, as well as for all pregnant women with certain medical conditions such as asthma. This is based on published reports that identify women in the later stages of pregnancy as being at increased risk for serious flu-related illness. Experts disagree about the effects of maternal influenza on unborn babies.

The goal of a recent study led by researchers at Vanderbilt University was to examine the impact of respiratory hospitalization during pregnancy on serious maternal and perinatal morbidity. The study was funded in part by the Agency for Healthcare Research and Quality through the Centers for Education and Research on Therapeutics (CERTs) program (HS10384).

The researchers performed a matched cohort study involving 294 pregnant women enrolled in the Tennessee Medicaid program during the eight study seasons (1985-1993) who had an acute cardiopulmonary hospitalization during flu season and 590 women without such hospitalizations. The two groups of women were matched by age, race, trimester of pregnancy, and presence or absence of high-risk conditions.

During eight consecutive flu seasons, 297 pregnant women in the study population had a respiratory disease hospitalization. Hospitalized women were older and had a higher prevalence of asthma (50 percent) and other high-risk conditions than the source population.

Overall, perinatal outcomes did not differ between women hospitalized for respiratory illness and their matched controls. Women hospitalized with a diagnosis of pneumonia and/or influenza (92 women) had nearly twice the rate of low and very low birthweight infants compared with women in the control group (15 percent vs. 9 percent), but this difference was not statistically significant. Although there was no significant association between respiratory hospitalization during flu season and adverse perinatal outcomes, the researchers conclude that pregnant women should be encouraged to receive influenza vaccination.

See "Maternal morbidity and perinatal outcomes among pregnant women with respiratory hospitalizations during influenza season," by Tina V. Hartert, M.D., M.P.H., Kathleen M. Neuzil, M.D., M.P.H., Ayumi K. Shintani, Ph.D., M.P.H., and others, in the American Journal of Obstetrics & Gynecology 189, pp. 1705-1712.

Return to Contents
Proceed to Next Article

The information on this page is archived and provided for reference purposes only.


AHRQ Advancing Excellence in Health Care