Health & Pregnancy

More Pregnant Women Getting Flu Shots

Flu Vaccine Protects Newborns

A second study, conducted at the University of Utah, confirmed that pregnant women who get the seasonal flu vaccine pass their immunity to their babies and that the protection lasts for two months after birth.

The researchers studied 27 women, 11 (41%) of whom received the seasonal influenza vaccine. All babies born to immunized women had flu antibodies in their blood at birth, compared to 31% of babies born to women who had not received the vaccine.

At two months, 60% of babies born to immunized women had antibody protection vs. none of the babies born to women who weren't vaccinated.

By four months, however, there was no difference in antibody rates between the two groups.

But wouldn't it have been better to compare the rates of flu and flu complications among the two groups than antibody rates?

Yes, says study researcher Julie H. Shakib, DO, MPH, assistant professor of pediatrics at the University of Utah in Salt Lake City. "But we need a much larger study to do that."

On the other hand, antibody rates are a reasonable substitute for flu rates, Shakib and Neuzil agree. Other research has shown an association between the two, they explain.

Flu Vaccine Not Linked to Miscarriage

The third study, the largest to date on the topic, showed there is no association between getting the flu vaccine during the first trimester of pregnancy and miscarriage.

Researchers at the Marshfield Clinic Research Foundation in Marshfield, Wis., compared the medical records of 243 pregnant women who had a miscarriage and 243 who did not.

A total of 38 women (16%) who miscarried had received the influenza vaccine in the four weeks before the pregnancy loss, compared to 31 women (13%) who did not miscarry. That's a difference so small it could be due to chance.

"Although there was never any hard evidence that influenza vaccine can cause pregnancy loss, there have been fears about it," study researcher Stephanie A. Irving, MS, an epidemiologist at Marshfield, tells WebMD.

"This study should provide reassurance," she says.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.