Opportunities to prevent the infection are being missed in hospitals across Britain, charities said.
Group B Streptococcus (GBS) is the most common cause of meningitis in young babies, triggering an estimated 500 cases a year.
The infection can be prevented by giving antibiotics to at-risk mothers during delivery.
Researchers who looked at data from 202 of the 222 Neonatal Units across Britain and the Republic of Ireland insist that up to 50 per cent of case could be avoided if more mothers were given the drugs.
But they found that many women were not even warned about the infection.
The warning was made by the charities Meningitis Research Foundation (MRF) and Group B Strep Support.
Many women carry the infection without showing any symptoms.
Although there are no reliable figures for how many have GBS one in 10 people carry a form of meningitis infection at some point in their lives.
“At risk” women include those whose temperatures spike during labour, who give birth more than 18 hours after their water breaks or who have had another child who suffered from the infection.
Babies under 12 months of age are 38 times more likely to contract the infection than older children or adults.
Dr Paul Heath, from St George’s University of London, who led the team which analysed the figures, warned: “The early treatment of meningitis in babies appears to vary widely across Britain.”
Christopher Head, chief executive of the MRF, said: “(We are) very concerned by the lack of awareness of GBS infection and the potential inconsistencies in the treatment of the disease.”
The organisation is launching a new research project to improve recognition and treatment of meningitis in young babies.
Around 1,000 children under the age of one develop meningitis in Britain and the Republic of Ireland every year.