Yellow fever is a potentially life-threatening mosquito-borne viral infection endemic to rural areas of sub-Saharan Africa and tropical regions of South America. The yellow fever vaccine is a live attenuated vaccine indicated for providing active immunisation for people travelling to, or residing within, yellow fever endemic areas, or countries which require an International Certificate of Vaccination and those handling potentially infectious material (e.g. laboratory personnel).

Live vaccines including the yellow fever vaccine are generally contraindicated in pregnancy due to the theoretical risk of strain reversion and congenital infection following gestational exposure. Unvaccinated pregnant women are therefore advised to avoid travelling to yellow fever-endemic areas and handling potentially infected material. Where travel or contact is unavoidable, vaccination in pregnancy should be considered on a case-by case basis. The possible fetal risks of vaccination should be weighed against the risk to mother and fetus from yellow fever infection which is associated with significant morbidity and mortality, particularly in immune-naïve individuals.

The available published data are limited to approximately 2,000 unique cases of intrauterine exposure. These data do not demonstrate an increase in risk of adverse pregnancy outcomes following gestational exposure to yellow fever vaccine.

Following vaccination against yellow fever, immunity is usually acquired within ten days. However, evidence from a small sample of pregnant women has suggested that gestational stage at vaccination can affect seroconversion. Women vaccinated in the third trimester should therefore be vigilant in identifying symptoms of infection following potential exposure.