Vaccinating against H1N1 during pregnancy may cut premature birth risk

Pregnant women receiving the H1N1 influenza vaccine were found less likely to have a preterm or smaller than normal baby, according to a prospective study published in the American Journal of Public Health.

In addition, the vaccine also appeared to reduce the risk of fetal death. Canadian researchers in Ontario analyzed data from 55,570 women who gave birth from November 2009 to April 2010. The H1N1 vaccine was administered to 23,340 of the women during the second or third trimester of pregnancy, reports.

The study showed that vaccinated mothers were less likely to have a baby born at less than 32 weeks of gestation and less likely to have a baby small for its gestational age. Fetal death was also found to be less likely among the babies of the vaccinated mothers. The researchers warned that their findings are preliminary and must be confirmed in future studies.

The authors also noted that the effectiveness of a particular flu vaccine is specific to the strains circulating during a certain season. As a result, the benefit of the vaccine could not be appreciable in future seasons with a less precise match between the circulating virus and the vaccine or a lower morbidity rate, according to

In 2009 during the H1N1 pandemic, pregnant women in the United Kingdom were included in one of the clinically at-risk priority groups to receive the swine flu vaccine.