Expectant mothers who receive the seasonal flu vaccine may be at significantly lower risk for stillbirth than those who are not vaccinated. This is the conclusion of a new study published in the journal Clinical Infectious Diseases.

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Expectant mothers who received the seasonal flu shot were found to be at 51% lower stillbirth risk than those who were not vaccinated.

In the US, around 1% of all pregnancies are affected by stillbirth, and around 24,000 babies are stillborn every year.

While the causes of many stillbirths are unclear, birth defects, genetic problems, issues with the placenta or umbilical cord and certain medical conditions in the mother can play a role.

Expectant mothers who are over the age of 35, smoke during pregnancy, obese, have experienced a previous pregnancy loss or who have had multiple pregnancies are also at greater risk for stillbirth.

Because many stillbirths are unexplained, identifying preventive strategies proves challenging.

But in a new study, coauthor Annette Regan, of the Western Australia Department of Health, and colleagues suggest the annual flu vaccine may protect against stillbirth.

Using the records of midwives, the team analyzed 58,008 births that occurred in Western Australia between April 2012 and December 2013.

Of these births, 52,932 occurred among women who had received the seasonal trivalent influenza vaccine during pregnancy, while 5,076 occurred among women who had not received the vaccine.

Compared with women who had not received the flu vaccine during pregnancy, the researchers found that those who had were at 51% lower risk of experiencing a stillbirth.

Furthermore, the researchers identified a rise in stillbirth rates following periods of influenza virus circulation, while stillbirth rates fell in the months before circulation. However, they note that this particular finding was not statistically significant.

Still, the authors believe their findings indicate that seasonal flu vaccination may protect pregnant women against stillbirth.

Regan says:

During the 2009 H1N1 pandemic, we saw a similar reduction in stillbirths following vaccination. Our results are particularly exciting since they show we can get the same protection during seasonal epidemics, which occur every winter. Unfortunately, we know that about 40% of pregnant women go unvaccinated, missing out on these benefits.”

The Centers for Disease Control and Prevention (CDC) recommend that all individuals aged 6 months and older – including pregnant women – receive a flu vaccination every year.

Pregnant women are at greater risk of developing flu-related complications, including pneumonia, bronchitis, sinus infections and ear infections. They may also be at higher risk for poor pregnancy outcomes, including preterm birth and fetal death.

However, despite the CDC stating that the flu vaccine is safe during pregnancy, many expectant mothers remain concerned that it may cause harm to their baby.

While Regan and colleagues say further research is warranted to better establish the links between flu, seasonal flu vaccination and stillbirth risk, they believe their current findings suggest the vaccine is safe for expectant mothers.

What is more, the researchers note that because of the data methods used in this study, it is likely benefits of seasonal flu vaccination for stillbirth have been underestimated.

“I’m hoping results like these can convince more pregnant women to get vaccinated each year,” adds Regan.

Earlier this year, Medical News Today reported on a study in which researchers found that the average global stillbirth rate fell between 2000-2015, although they state that it is still too high.