Aim of the programme The programme protects infants by boosting pertussis immunity in pregnant women, which enables the mother to transfer a high level of pertussis antibodies across the placenta to her unborn child. This has been shown to passively protect infants against pertussis from birth until they are due their first dose of primary immunisations at 8 weeks of age. The maternal antibodies will be naturally broken down by the infant in their first months of life. Although most women will have been vaccinated or exposed to natural whooping cough in childhood, receiving a pertussis-containing vaccine from week 16 of their pregnancy will temporarily boost their antibody levels. Whilst it is recommended that women are offered the vaccine between weeks 16 to 32 of pregnancy, usually around the time of the fetal anomaly scan (20 weeks), women may still be immunised after week 32 of pregnancy until delivery. However, this may not offer as high a level of passive protection to the baby, particularly if they are born pre-term. Safety of vaccine administration during pregnancy There are no concerns about the safety of the inactivated pertussis-containing vaccine at any stage in pregnancy. Inactivated vaccines contain no live organisms, cannot replicate and therefore cannot cause infection in either the mother or the fetus. Since the introduction of the pertussis vaccine in pregnancy programme in October 2012, the Medicines and Healthcare products Regulatory Agency (MHRA) has continually monitored the frequency and type of adverse events using the Yellow Card Scheme and additionally used the Clinical Practice Research Datalink to study pregnancy outcomes following vaccination. The MHRA found no safety concerns relating to pertussis vaccination in pregnancy based on a large observational cohort study of 18,000 vaccinated women with similar rates of normal, healthy births in vaccinated and in unvaccinated women. The study found no evidence of an increased risk of stillbirth in the 14 days immediately after vaccination or later in pregnancy and found no evidence of an increased risk of any of an extensive predefined list of adverse events related to pregnancy. Other studies have similarly not identified safety concerns (4). Pertussis-containing vaccines are routinely given during pregnancy in vaccination programmes in many other countries, including the US, New Zealand and Australia, so there is an increasing body of evidence to support the safety of pertussis immunisation during pregnancy. No increased risk for the development of severe maternal adverse events (for example, postpartum endometritis, preterm delivery, and preterm premature rupture of membranes) or fetal and neonatal outcomes (for example, low birth weight, very low birth weight, small for gestational age, birth defects, and need for neonatal intensive care unit admission) has been identified (5) A Canadian study (6) followed children up to their sixth birthday and found no significant increased risk in adverse childhood outcomes and pre-natal pertussis vaccination.