A study published in The BMJ found there was no link between mothers getting vaccinated for flu during pregnancy and health problems in young children.
“It is our duty to be clear: vaccination of pregnant women saves lives”
Researchers hope the findings will provide added reassurance to families across the world and help address low uptake of the vaccine in many countries including the UK.
Pregnant women and their newborn babies are considered to be at high risk of serious illness during flu pandemics and seasonal outbreaks.
As a result, many countries – including the UK – advise all pregnant women to have a flu vaccine, which can protect both mothers and their young children from the flu virus.
However, many women do not get the jab with safety concerns a common reason for not being immunised especially across Europe and the US.
There is plenty of evidence to show flu vaccination does not affect the health of newborn babies whose mothers were vaccinated while pregnant.
But few studies have looked at the health of older children who were exposed to the flu jab while in the womb.
In this latest study researchers from Canada and the US set out to explore the relationship between the 2009 H1N1 “swine flu” vaccine during pregnancy and the health of children aged up to five.
They looked at records for all babies born in Ontario, Canada from November 2009 to October 2010. Of nearly 104,250 children born during that period 30% – nearly 31,300 children in all – were born to vaccinated mothers.
The researchers tracked the health of children over five years and found no increased risk of cancer, infections, chronic diseases, hospital admissions or death among those whose mothers had been vaccinated.
They found the incidence of childhood gastrointestinal infections was slightly lower in children born to vaccinated mothers while the risk of childhood asthma appeared to be slightly higher.
However, they stressed these associations were “very small” and may be due to other factors not included in the analysis.
While the study was not designed to establish cause and effect, the researchers said the results were “reassuring” and consistent with other research that suggests the vaccine they looked at was safe to use during pregnancy.
Further studies looking at different flu vaccines – including those used to treat seasonal flu – would be useful, they added.
In a linked editorial, Siri Håberg from the Norwegian Institute of Public Health’s Centre for Fertility and Health and Allen Wilcox, a scientist at the National Institute for Environmental Health Sciences in the US, said the findings added to strong evidence that flu vaccination during pregnancy was safe.
“The message is clear: influenza vaccination during pregnancy is, by all available evidence, safe for mother and offspring,” they wrote.
“Especially in this era of ‘anti-vaxx’ anxiety and misinformation, it is our duty to be clear: vaccination of pregnant women saves lives,” they concluded.