A new study shows an unexpected beneficial side effect to the H1N1 vaccine in pregnant women. Several years ago there was debate about the health risks this vaccine could have on expectant mothers. During the 2009 outbreak little was known about the vaccine, now Canadian researchers have data to suggest the flu shot reduced risk of stillbirth, preterm birth and extremely small babies at birth.
The unknown side effects
Researchers examined 55,570 single-child births that took place in Ontario during the H1N1 pandemic and found that, compared to pregnant women who were not immunized against H1N1, mothers who received the H1N1 vaccination were:
- 34% less likely to have a stillbirth,
- 28% less likely to deliver before 32 weeks, and
- 19% less likely to give birth to a child with a birth weight for gestational age in the bottom third percentile.
“These are all significant results, but especially interesting is the finding that the vaccinated mothers were one-third less likely to have a stillborn child,” says lead author Deshayne Fell, an epidemiologist for BORN Ontario. “This is one of the only studies large enough to evaluate the association between maternal flu vaccination and stillbirth—a very rare event.”
“What surprised me and the research team was the strength of the protective benefits we found,” says co-author Dr. Ann Sprague, the Scientific Manager of BORN Ontario at the Children’s Hospital of Eastern Ontario (CHEO) Research Institute.
Learning for the future
Doctor’s say this data provides support for the vaccine, should it be needed in the future.
“Pregnant women are generally very, very careful about what they put into their bodies. For health-care providers like me, such a large-scale study that shows no adverse perinatal outcomes resulting from the H1N1 flu vaccine will be extremely helpful when discussing maternal vaccination.”
