For the first time all pregnant women are being offered the seasonal flu jab.
The government has approved the move in response to the risk of swine flu, which is believed to be still circulating.
Pregnant women are at a higher risk from the virus, but the jab will protect them against it as well as two other flu strains.
More than 14 million people in the ‘at-risk group’, including over 65s, people with conditions such as diabetes and health workers, are still eligible for the injection.
Around 75% of over 65s, 50% of people with health conditions and 10% of health workers have the jab, but the Department of Health is urging all those entitled to get the vaccine.
The government’s director of immunisation Professor David Salisbury said patients would be “foolhardy” not to have it because of fears about the swine flu strain.
He said: “To not have the vaccine because of a prejudice about swine flu is putting yourself at unnecessary risk. That attitude is ignoring the realities of the risk.”
GPs have already started receiving the vaccine and should complete the programme by December.