The question of whether or not to vaccinate against the flu is just one of many decisions pregnant women must make. However, a new large national study may put some fears to rest after revealing evidence that the H1N1 vaccine is safe during pregnancy.

A collaboration between researchers from the University of California-San Diego (UCSD), Boston University, and the American Academy of Allergy Asthma and Immunology (AAAAI) yielded one large national study and two companion papers published in the journal Vaccine.

The researchers say that despite federal health recommendations that all pregnant women be vaccinated for the flu, less than 50% of women follow the advice, most likely because they are worried about how the flu vaccines might affect the baby.

However, recent studies have shown that babies of mothers who have the flu during pregnancy can face certain adverse effects. One study, for example, revealed that flu in pregnancy increases a child’s risk of bipolar disorder.

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Contracting the flu during pregnancy can bring risks for the baby, but researchers have confirmed that pregnant women can safely get the H1N1 flu shot without putting their baby at risk.

Health officials anticipated that the 2009 H1N1 flu season would be tough, so the Vaccines and Medications in Pregnancy Surveillance System (VAMPSS) launched a national study to gather data on the safety of the H1N1 vaccine during pregnancy.

Researchers from UCSD, led by Dr. Christina Chambers, followed 1,032 pregnant women in the US and Canada who either were or were not vaccinated between 2009 and 2012.

They found that the pregnant women who were vaccinated were no more likely to have a miscarriage, a baby born with a birth defect or a baby born smaller than normal, compared with the women who did not get a vaccination.

Though the vaccinated women were more likely to have their babies early, it was, on average, only 3 days earlier than the unvaccinated women.

In another study, this time from the VAMPSS team at Boston University, researchers studied 4,191 pregnant women in the US who had delivered either a normal infant or an infant with one of 41 specific birth defects.

After comparing influenza vaccine use in the two groups from 2009-2011, the research revealed that there was “no significant evidence of an increased risk of any specific birth defects.”

Pregnant women who received the H1N1 vaccine in this study during 2009-2010 delivered an average of 2 days earlier than women in the unvaccinated group, but for vaccinated women during 2010-2011, the opposite was the case, with unvaccinated women more likely to deliver preterm.

Dr. Christina Chambers says that the study’s results are “reassuring” about flu vaccine safety, adding:

We believe our study’s results can help women and their doctors become better informed about the benefits and risks of flu vaccination during pregnancy.”

Carol Louik, lead investigator from the Boston University team adds, “A concern about the risk of specific birth defects was a critical question that has not been considered very much until now, and our data are reassuring.”

The Centers for Disease Control and Prevention (CDC) recommends that pregnant women get a flu shot and also provides 6 steps that can help to stop germs from spreading:

  1. Avoid close contact
  2. Stay home when you are sick
  3. Cover your mouth and nose
  4. Wash hands often
  5. Avoid touching eyes, nose or mouth
  6. Practice other health habits, such as getting plenty of sleep and drinking lots of fluids.

Medical News Today recently reported that scientists are closer to a universal flu vaccine, after a recent natural immunity study.