Influenza Vaccine During Pregnancy Associated with Lower Risk of Preterm Birth, Stillbirth, and Infant Mortality

The influenza vaccine can decrease your risk of getting the flu or at least decrease the severity of the flu. It can be particularly important for people who are more vulnerable to serious flu complications like women who are pregnant. The immune system is lower during pregnancy, meaning the mother is more susceptible to flu complications that can lead to serious problems for both the mother and the baby. As a result, flu vaccines are recommended for women who are pregnant or planning on becoming pregnant.

Researchers from Texas wanted to examine safety outcomes in babies whose mothers had an influenza vaccine during pregnancy. The study, published in Obstetrics and Gynecology, found that vaccination during pregnancy was associated with benefits and fewer negative outcomes for the baby.

About the Study

The cohort study included 85,783 women who gave birth between October 2003 to March 2008. About 10.3% of the women had received an influenza vaccination during pregnancy. They all received the recommended inactive form of the vaccine. The vaccines were delivered in the first trimester in 439 women and the second or third trimester in 8,251 women.

Children born to mothers who received an influenza vaccine did not have a higher risk of major malformations than children born to mothers who did not receive a vaccination. Babies born to mothers with vaccination had lower rates of neonatal death, preterm birth, or stillbirth. These benefits applied regardless of when the vaccine was delivered.

How Does This Affect You?

A cohort study is an observational study. This means researchers do not control factors in the study, but simply observe the outcomes. This means there are many factors that can influence the outcomes. This type of study is used to look for potential links but can not be used to confirm cause and effect. Doing a randomized trial would help remove the other influencing factors, but this type of study is not often done in pregnant women due to ethical reasons. Since this is the case, a cohort study is usual done in this population.

Influenza vaccinations are intensely studied each year. They are followed to check for protective effects and any unwanted side effects. This study adds to growing data that the flu vaccine is safe for pregnant women and their babies. In addition there is plenty of evidence that women who are pregnant are more susceptible to severe flu symptoms which can effect the health of their baby. This is why the Centers for Disease Control and Prevention (CDC) strongly recommends that pregnant women and women planning on becoming pregnant get their flu shot. Talk to your doctor about the flu and other vaccination if you are planning a pregnancy or you are pregnant.


Centers for Disease Control and Prevention


Sheffield JS, Greer LG, Rogers VL, et al. Effect of influenza vaccination in the first trimester of pregnancy. Obstet Gynecol. 2012 Sep;120(3):532-7
Last reviewed November 2012 by Brian P. Randall, MD

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