The flu vaccine may be causing Pregnant Women to have miscarriages. While not finding a definitive link, a recent study from the Marshfield Clinic Research Institute suggests pregnant women who experienced an unsuccessful pregnancy had also received the annual flu vaccine just before the miscarriage.

The study, co-authored by senior epidemiologist Edward Belongia, examined medical records from women who had a miscarriage between 2010 and 2012. The researchers noticed that these particular women also received the flu vaccine in those same years. However, the authors are quick to note that this means there is a possible association, not a certain, causal one.

Not enough study participants

After reviewing the cases of 485 pregnant women between the ages of 18 and 44 who suffered a miscarriage, the researchers found 17 received the flu vaccine the month before. They also got the flu shot the year prior. In addition, researchers looked at medical records for 485 pregnant women who had normal, healthy deliveries. Of those, only four received the flu vaccine during the pregnancy as well as the year before.

Too many inconsistencies

While the findings loosely associate the vaccine with miscarriage, the study had several variables that could also explain the failed pregnancies. Compared to the successful pregnancy group, more women in the miscarriage group were older, smokers, and diabetic. The researchers attempted to make adjustments for the variables but admitted that there may still be inconsistencies in the findings.

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The scientists did previous studies on the potential link between the flu vaccine and miscarriages for the 2005-2006 and 2006-2007 flu seasons. The results of those did not yield any potential relationship.

CDC still recommends vaccine

The Centers for Disease Control and Prevention (CDC) continue to recommend the Flu Shot for pregnant women no matter what stage they are in. The recent flu shot and miscarriage study does not provide enough evidence for the agency to change its stance. However, the CDC predicts that news of the study will raise concern among pregnant women. Agency officials contacted various organizations, including the American Congress of Obstetricians, to remind them that the research is inconclusive and pregnant women should not stop getting flu immunizations just yet.

More research needed

Currently, a larger study is being conducted to verify if a link between the flu shot and miscarriages exists. The results of this study will not be published until next year.