The whooping cough vaccine in pregnancy

The UK’s Medicines and Healthcare products Regulatory Authority (MHRA) recently carried out a study of more than 20,000 pregnant women in the UK who have received the pertussis (whooping cough) vaccine. The study assessed the safety of the vaccine in pregnancy and found no risk to the baby or the mother associated with the vaccine. This is an important study showing the safety of the pertussis vaccine for the unborn child.

In 2012 the UK experienced an epidemic of pertussis (whooping cough), in which 14 babies under 3 months of age died. All of them were too young to be protected against pertussis by routine immunisation; protection is low until babies receive their second dose of the 5-in-1 vaccine at 3 months of age. As a result the UK Department of Health advised that all pregnant women should be vaccinated against pertussis (ideally between 24 and 32 weeks) to give protection to their unborn child, as protection is passed from the mother to the baby before birth. (See our page on the pertussis vaccine in pregnancy for more detailed information.)

Since then up to 60% of pregnant women in the UK have chosen to have the pertussis vaccine, and the number of very young babies affected by pertussis has fallen. But levels of pertussis are still higher than usual, and the UK government recently decided to extend the programme of pertussis vaccination in pregnancy for at least another 5 years to reduce the risk of young babies dying from this disease.

The vaccine offered to pregnant women is one of the pre-school booster vaccines. In the USA similar vaccines have been used in pregnancy since 2011 and there have been no safety concerns. However, the vaccines have not been formally evaluated for use in pregnancy in large controlled studies, and this means that so far there has been no specific safety data that pregnant women could refer to.

The MHRA study compared 20,076 pregnant women who had received the pertussis vaccine with a similar sized group who had not. The study found no evidence that any of the following risks were increased as a result of the pertussis vaccine given in pregnancy:

  • Stillbirth
  • Premature birth or low birth weight
  • Death of the mother
  • Death of the newborn baby
  • Pre-eclampsia
  • Haemorrhage
  • Foetal distress
  • The need for caesarean delivery
  • Renal failure of the newborn baby

Vaccinating pregnant women is the best way to protect newborn babies from pertussis, and it’s expected that these new data will reassure more pregnant women that it is safe to take up the offer of vaccination.

Read the abstract of the MHRA study in the British Medical Journal