31 March 2016

Influenza vaccination during pregnancy may reduce stillbirth risk

WA Health researchers, in collaboration with the Telethon Kids Institute, have discovered that pregnant women who receive the seasonal influenza vaccination are less likely to experience a stillbirth than unvaccinated mothers.

The retrospective study used records to examine nearly 60,000 Western Australian births that occurred during the 2012 and 2013 seasonal influenza epidemics. The cohort included 52,932 mothers who had not received the vaccine and 5076 mothers who had been vaccinated.

The risk of stillbirth among vaccinated mothers was 51 per cent lower than the risk among women who had not been vaccinated.

WA Health Communicable Disease Control Directorate Project Officer and study author Annette Regan said that the results were particularly exciting as it showed vaccination could help reduce the stillbirth rates for mothers-to-be.

“It is widely accepted that pregnancy puts women at an increased risk of developing serious complications related to influenza, including acute respiratory distress syndrome and pneumonia. This study also suggests that foetal mortality is linked to influenza infection during pregnancy,” she said.

“In the past 12 months there has been a significant uptake in the number of pregnant women receiving the antenatal pertussis vaccination, yet the number of women receiving the antenatal influenza vaccination is still low.

“Approximately 40 per cent of pregnant women in Western Australia do not receive the influenza vaccine, which means both they and their unborn baby are missing out on protection. This lower uptake rate may be due to concerns about the safety of influenza vaccination during pregnancy.

“As a direct result of this research WA Health will be broadening its 2016 seasonal influenza vaccination promotions to better educate consumers and health professionals on the health benefits of the influenza vaccination during pregnancy.”

The research published today in the Clinical Infectious Diseases Journal (external site) by the Infectious Disease Society of America (IDSA) (external site), also showed that stillbirth rates increased after influenza virus circulation periods and decreased prior to the influenza season.

Although these seasonal differences were not statistically significant, they were consistent with results from a study in Switzerland in 2000 which showed the incidence of stillbirth increased in relation to the northern hemisphere’s influenza season, as well as with similar research conducted during the influenza A/H1N1 pandemic.

“The findings support the safety of influenza vaccination during pregnancy, and also suggest that vaccination protects against stillbirth,” Ms Regan said.

“With more than three million stillbirths occurring worldwide each year, establishing a connection between influenza season, vaccination and stillbirth could have global implications for infant mortality.

“While further research is needed to confirm these links, the findings of this study should encourage expectant mothers and health care providers to discuss the safety and benefits of receiving the influenza vaccine during pregnancy.”

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