Researchers from the US Centers for Disease Control and Prevention in Atlanta, Georgia, studied 1,169 mothers with healthy babies born during three influenza seasons.
In the UK, children in at-risk groups are only offered the seasonal flu vaccine after six months of age. But during severe flu outbreaks younger children may be at risk of infection.
In the study, mothers were questioned as to whether they received the flu jab and cord blood was taken to measure flu anti-body titres postpartum.
Parents were asked to report if their child experienced a flu-like illness. The diagnosis of flu was then confirmed by laboratory testing.
Children of vaccinated mothers had a 41% lower risk of contracting flu than those born to unvaccinated women.
Vaccinated mothers had children with significantly higher flu antibody titres leading to greater flu protection and lower risk of hospitalisation due to flu.
The researchers said: ‘Although influenza vaccination is recommended for pregnant women to reduce their risk of influenza complications, these findings provide support for the added benefit of protecting infants from influenza virus infection up to six months.’