Flu Vaccinations in Pregnant Women May Protect Against Stillbirths
Researchers from Western Australia have reported that seasonal influenza vaccinations may protect against stillbirth. Findings from the study are published in Clinical Infectious Diseases.
The retrospective study analyzed 58,008 births that occurred during the southern hemisphere's 2012/2013 seasonal influenza epidemic, using midwives' records. They found that women who received the trivalent influenza vaccine during pregnancy had a 51% reduced risk of experiencing a stillbirth vs. women who were unvaccinated.
They also noted that rates of stillbirth rose after periods of influenza virus circulation and decreased during the months prior to the influenza season; though these seasonal differences were not statistically significant. These findings were similar to those of a 2000 Swiss study that documented a higher incidence of stillbirth in relation to the northern hemisphere's influenza season, and also the influenza A/H1N1 pandemic.
The Centers for Disease Control and Prevention (CDC) recommends annual influenza vaccination for everyone aged ≥6 months, including pregnant women during any trimester of their pregnancy. Many pregnant women opt out of vaccination due to concerns over fetal safety, however the new data supports influenza vaccination safety during pregnancy and suggests that it may protect against stillbirth.
The study authors added that the protective benefits seen in the study "may be an underestimate of the true effect measure" due to the methods of data analysis used in the study. More studies are needed to confirm the associations between stillbirth, influenza season, and vaccination.
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