A huge rise in whooping cough cases has been recorded in Lincolnshire.
Figures released by the Health Protection Agency (HPA) show that there have been 65 incidents in 2012 to date.
There were less than ten cases confirmed in each of the previous four years.
The dramatic rise has been put down to a natural cycle.
And it has sparked a new vaccination programme by the Department of Health.
Women who are between 28 and 38 weeks pregnant will be offered the immunisation to protect their unborn child until they are old enough to be immunised themselves.
United Lincolnshire Hospitals Trust said there had not been any babies admitted for the condition.
Spokesman for NHS Lincolnshire, Sarah Howells, said: "The Department of Health has taken the decision to launch a temporary vaccination programme to offer pregnant women a vaccine against pertussis, also known as whooping cough. The NHS in Lincolnshire is working to implement the vaccination programme and GPs will invite all pregnant women over 28 weeks for a vaccination.
"The Joint Committee on Vaccination and Immunisation has recommended this action following a recent rise in the number of cases in the UK.
"The vaccination programme will be kept under review nationally to confirm whether it will be continued or stopped."
The vaccine, Repevax, will be offered during routine antenatal appointments with a nurse, midwife or GP.
It is similar to one currently used in the US and protects against whooping cough, diphtheria, tetanus and polio.
Louise Silverton, deputy general secretary of the Royal College of Midwives, said: "This campaign has our full support.
"Whooping cough is on the increase among young babies and it can be a dangerous and potentially fatal infection.
"We encourage pregnant women to have the vaccination in the final trimester of pregnancy to protect themselves and their baby from the disease in the first weeks after it is born.
"Having the vaccination will also help to stop the spread of the disease to other people.
"If any pregnant woman is unsure about this I would encourage them to speak to their midwife or doctor to discuss the issue.
Dr Mary Ramsay, head of immunisation at the HPA, said: "We have been very concerned about the continuing increase in whooping cough cases."