Flu Vaccine Protects Newborns in Multiple Ways-EMBARGOED 21-Feb-2012 12:00 ET

Pregnant women vaccinated against the flu had more babies of a healthy size

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(RxWiki News) The flu vaccine can do more than protect a pregnant mother and her baby from the flu. It also appears to reduce the risk of having an underweight baby.

A new study comparing women who received the flu vaccine while pregnant with those who did not revealed that the flu-vaccinated women had fewer underweight babies during flu season.

"Get the flu vaccine when you're pregnant."

Dr. Mark Steinhoff, of the Cincinnati Children's Medical Center, and colleagues ran a randomized controlled trial with 340 healthy pregnant women in Bangladesh from August 2004 to December 2005.

The study was part of the Mother's Gift project, which investigates the safety and effectiveness of pneumcoccal and flu vaccines in Bangladeshi pregnant women.

Approximately half the women were given the inactivated influenza vaccine, and the control group were given the pneumococcal vaccine.

When comparing the women who had a flu vaccine to those who did not, Steinhoff's team found that more of those without the vaccine gave birth to underweight babies when the virus had been present in their environment.

Among vaccinated women, 26 percent of the babies were small for their gestational age, but 45 percent of the babies born to the control group of mothers were small.

This was only true while the virus was circulating, however, from September 2004 through January 2005. When the virus was dormant, from February through October 2005, the percentage of underweight babies was about the same in both groups.

The average weight of babies born to the vaccinated mothers was 7 pounds, compared to 6.6 pounds in the group born to women who did not receive the vaccine.

"We found that immunization against influenza during pregnancy had a substantial effect on mean birth weight and the proportion of infants who were small for gestational age," the authors wrote.

"Our data suggest that the prevention of infection with seasonal influenza in pregnant women by vaccination can influence fetal growth," they state.

The authors conclude that, if additional research shows similar results, adding the flu vaccine to routine vaccination programs during pregnancy would be advantageous for the infants.

The study appeared online February 21 in the Canadian Medical Association Journal. The authors had no declared conflicts of interest.

The research was funded by the Bill and Melinda Gates Foundation, U.S.A.I.D., Wyeth Pharmaceuticals, the Thrasher Research Fund, Aventis Pasteur, the International Centre for Diarrheal Disease Research in Bangladesh, and the Bloomberg School of Public Health at Johns Hopkins University.

Last Updated:
February 20, 2012