Getting the flu during a pregnancy can be riskier than most, leading to hospitalization for severe symptoms. The virus can even result in preterm birth or miscarriage, threatening the lives of both mother and baby.
Because of this, experts recommend that expectant mothers get the flu vaccine, calling it an “essential” part of prenatal care, NPR reports.
A study looking at the effects of the vaccine in pregnant women turned up some unexpected results. Dr. Edward Belongia, director of clinical epidemiology and population health at the Marshfield Clinic in Wisconsin and member of the Centers for Disease Control and Prevention’s advisory committee on immunization practices, said, “We knew this would be controversial when it was published. This was an unexpected safety signal. This is not what we were looking for.”
Belongia added, “I believe the best approach with the public is to be very clear and open and transparent about ‘Here’s what we know; here are the limitations; here’s why we still recommend the flu vaccine during pregnancy.’”
Their study followed up on Belongia’s previous work that found no link between miscarriage and the flu vaccine. It examined pregnant women in 2005-2007, before the 2000 H1N1 flu pandemic that led to the creation of a new vaccine.
James Donahue, lead author on the study and senior epidemiologist at the Marshfield Clinic, said,
The CDC was very interested to make sure that we were still seeing the same safety profile for this new vaccine, and so asked us to do another study.
This recent study looked at pregnant women in 2010-2012, and found an association between the flu vaccine and miscarriage in the first term. However, there was no direct causal relationship established.
Miscarriage is common during the first trimester, though it’s hard to get exact numbers as some women may not even know they’re pregnant.
Despite the controversial nature of the study, the team decided to go ahead with publication. “The scientific literature is littered with things that were found unexpectedly and were later found to be not important — or even not true — so we’re very cognizant of that,” Donahue said. “But this is a safety signal we can’t explain away, and it clearly merits further investigation.”
The American College of Obstetricians and Gynecologists agrees, reminding women that the flu vaccine remains important in prenatal care, and that is protects both women and newborn babies. It is particularly important since the vaccine is not approved for babies younger than six months.
Belongia said, “It’s perfectly appropriate for any pregnant woman who hears about this and is concerned about this to talk to their obstetrician about the best timing for a vaccination based on her own circumstance.”