Flu vaccine poses no risk to unborn January 16, 2013 -- Updated 2303 GMT (0703 HKT) (CNN) -- Fears and misconceptions often surround the flu vaccine: Does it really work? Will it make me sick? Could it hurt my baby? Researchers from Norway say the last question was a big concern during the 2009 H1N1 pandemic; anecdotal reports of fetal deaths caused many pregnant women to avoid getting vaccinated despite health officials' pleas. To determine the accuracy of these reports, the Norwegian researchers analyzed data from more than 100,000 pregnancies during the 2009-2010 flu season. Their results were published this week in the New England Journal of Medicine. The study found no evidence that the influenza vaccine increased the risk of fetal death in pregnant women. But pregnant women who were diagnosed with the flu - whether they had the vaccine or not - had nearly double the risk of fetal death. The Centers for Disease Control and Prevention recommends all pregnant women get the flu shot (the nasal spray vaccine is not recommended for pregnant women) to protect them from the virus. But during the 2011-2012 flu season, only 47% opted to get vaccinated, according to the CDC. Pregnant mothers are just trying to do what's right, says Dr. Siobhan Dolan, co-author of March of Dimes' new book "Healthy Mom, Healthy Baby." Their fear often stems from the unknown, she says, which is why studies like the one publishing this week are important. "At this point we have mounting evidence - data and studies - that show it's not getting the shot that causes the problem, but getting the flu that's the problem," Dolan says. Even if you are healthy, changes to your immune system during pregnancy make you more likely to get seriously ill, Dolan says. Pregnant women are more likely to end up in the hospital after an influenza diagnosis, according to the CDC. Respiratory issues can also pose a danger. If a mother is having difficulty breathing, her baby isn't receiving enough oxygen. If you do get the flu, Dolan recommends asking your doctor about anti-viral medications that may help. The CDC says it's not too late to get the flu shot. The U.S. flu season runs from October to May. Antibodies from the shot will protect you and will be passed on to your baby, providing protection until 6 months of age.