Fewer than half of mothers-to-be have been vaccinated against whooping cough, despite a sharp increase in cases that has seen 13 babies die and several hundred others infected this year.

In October about 18,000 pregnant women in England received the vaccine, 44% of those eligible, according to Department of Health figures.

The government's immunisation chief, Professor David Salisbury, welcomed the 44% rate but said it was vital that every woman who is expecting a child should get immunised with the vaccine Repevax.

"I'm pleased that nearly half of pregnant women have taken up the offer of the whooping cough vaccine. But I'd urge all pregnant women between 28 and 38 weeks of pregnancy to get the vaccine to protect their babies," he said.

"Whooping cough is highly infectious and infants are particularly vulnerable."