"This is a very definitive study for a recent, relevant time period of flu and should remove all doubts a woman might have about whether it is safe to be vaccinated during pregnancy," said co-investigator Dr. Edward Belongia, director of the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute in Wisconsin, CNN reported.
The findings are based on an examination of the 2012-13, 2013-14 and 2014-15 flu seasons and were presented Wednesday to the U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.
The study comes at a time when there is significant focus in the U.S. on the consequences of certain groups telling people to ignore vaccine recommendations, CNN reported.
Not only is a flu shot during pregnancy safe, it's necessary, said lead investigator James Donahue, a senior epidemiologist at Marshfield.
"There's lots of evidence of the severity of flu for a pregnant woman, more chance of hospitalization, more risk of death, especially as she enters the second and third trimester," Donahue said, CNN reported.
"There are also many studies that show the mother's vaccination will help protect the newborn baby from flu, which is critical since the baby cannot be vaccinated until 6 months of age," he added.
CDC guidelines emphasize the importance of a flu shot during pregnancy.
"The findings provide a high level of reassurance regarding the safety of influenza vaccine in early pregnancy and through pregnancy and support the current recommendations of an influenza vaccination for all pregnant women," Donahue said, CNN reported.