The number of whooping cough cases recorded in the UK have soared to their highest levels in 20 years, with 13 babies dead from the disease in 2012.
Figures from the Health Protection Agency showed that three infants died from the disease in October alone.
There were 1,614 cases of whooping cough in England and Wales that month, bringing the year's total to 7,728 - 10 times higher than the same period in 2008.
The area worst affected by whooping cough was the southeast, with 1,478 cases recorded. Wales had the fewest cases, with just 243 infants contracting the disease.
The Department of Health said pregnant women would be offered the whooping cough vaccination to protect their unborn babies.
Normally, vaccinations against the disease do not start until the baby is two months old. The HPA reported 396 cases of whooping cough in babies under three months.
Whooping cough is a contagious bacterial infection that affects the lungs and airways. It normally begins with a persistent dry cough followed by a distinctive "whooping" noise.
Infected babies under the age of six months risk severe complications, such as breathing difficulties.
Signs and symptoms
Complications include pneumonia, dehydration, weight loss, seizures, kidney failure and brain damage from being starved of oxygen.
Gayatri Amirthalingam, consultant epidemiologist for immunisation at the HPA, said: "The October figures show a continuing rise in the overall number of whooping cough cases.
"While there has been a decline in the number of infant cases it's important to emphasise that it's too early to see any impact from the pregnancy vaccination programme.
"We strongly recommend all pregnant women take up the offer of vaccination. Parents should also ensure their children are vaccinated against whooping cough on time, even babies of women who've had the vaccine in pregnancy - this is to continue their baby's protection through childhood.
"Parents should also be alert to the signs and symptoms of whooping cough - which include severe coughing fits accompanied by the characteristic 'whoop' sound in young children but as a prolonged cough in older children or adults.
"It is also advisable to keep babies away from older siblings or adults who have the infection."
Worldwide, whooping cough causes almost 295,000 deaths every year.