Flu Shots Linked with Lower Stillbirth Rates

pregnancy, stethoscope
(Image credit: Pregnancy photo via Shutterstock)

Pregnant women who were vaccinated against the flu during the 2009 H1N1 pandemic had a higher chance of having a healthy baby, compared with those not vaccinated, a new study says.

Women who received the shot were 34 percent less likely to have a baby that was stillborn, 28 percent less likely to deliver before 32 weeks of pregnancy, and 19 percent less likely to have a baby with low birth weight, compared with women who did not receive the vaccination.

The Centers for Disease Control and Prevention already recommends the vaccine for pregnant women to protect against the flu, but the correlations between flu shots and lowered rates of stillbirth or early birth were unexpected, said study researcher Ann Sprague, of the Children’s Hospital of Eastern Ontario.

The study showed an association; the findings do not suggest that getting the flu shot caused reductions in a baby's health risks, and the results need to be confirmed in future studies.

The researchers used information from a Canadian database on the 55,570 single births delivered by mothers in Ontario between November 2009 and April 2010. Of the mothers, 42 percent received the vaccination. The researchers took into account factors such as the mothers' smoking and education levels, but said that still other factors might have influenced the results.

In the U.S., stillbirths occur in about one in 160 pregnancies, according to the March of Dimes.

Babies born before full term (37 weeks of pregnancy), and those born with low-birth weight, are more likely to have breathing and heart problems, as well as other complications.

There were no adverse affects for the mothers or children as a result of the vaccination, in the weeks leading up to or immediately following birth, according to the researchers, who said they will continue to follow the children throughout their first year to further examine the impact of the vaccine.

“Pregnant women are generally very, very careful about what they put into their bodies,” said study researcher Dr. Mark Walker, senior scientist at the Ottawa Hospital Research Institute. The findings will be helpful in discussions that doctors have with their pregnant patients about vaccinations, he said.

The findings were published in the June issue of the American Journal of Public Health.

Pass it on: The flu shot may not only protect pregnant moms from infection, it might also contribute to healthier births.

Live Science Staff
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