Pregnant woman have no increased risk of infant loss after a flu shot, one study seems to show.
The Norwegian study Risk of Fetal Death after Pandemic Influenza Virus Infection or Vaccination, found that vaccination reduced the risk of infant mortality and was not associated with increased foetal deaths.
Co-author Dr Allen Wilcox from the National Institute of Environmental Health Sciences (NIEHS) said: "Pregnant women should find it reassuring that we found no harmful effects on the fetus associated with H1N1 vaccination."
"If pregnant women are worried about their fetus, then getting a flu shot is a good thing to do."
Louise Silverman, director of midwifery at the Royal College of Midwives (RCM) said: "I'm delighted that more research has been done into carrying out vaccinations while pregnant.
"Safety is what pregnant women are concerned about, because we have always said they shouldn't take anything unnecessarily, however, there are serious risks to becoming ill while pregnant.
However, she added it "may take a while" for vaccinations during pregnancy to become common practice.
During the 'swine flu' pandemic in 2009 researchers from the US and Norwegian National Health Institutes examined the risks of flu vaccination to pregnancy.
Media reports of pregnancy losses after flu shots caused some expectant mothers to opt out of vaccination in Norway.
The study, published in the New England Journal of Medicine, suggested that pregnant women who caught the H1N1 variant could face double the chance of miscarriage or stillbirth.
Researchers looked at 117,000 pregnancies in Norway and found that the risk of foetal death was reduced with vaccination.
According to Health Protection Agency (HPA) figures, only 40% of pregnant women in the UK opted to have a flu jab this winter.
Professor Nick Phin, a flu surveillance expert at the Health Protection Agency (HPA), said: "It is now well-recognised that pregnant women are at significantly increased risk of complications, including death, from influenza infection - especially in the third trimester and up to two weeks after giving birth.
"Pregnant women should be reassured by this study that flu vaccination does not carry any risks for their baby and we hope it will encourage pregnant women who have not yet received their flu jab to make an appointment with their GP or midwife – flu is still circulating in the community and it's never too late to get vaccinated."