From the Guidelines
Pregnant women should not receive the MMR vaccine due to the theoretical risk of transmission of live attenuated viruses to the fetus, although the risk of congenital rubella syndrome from vaccination is considered to be zero to 1.6%. The primary concern is with the rubella component, which has been associated with congenital rubella syndrome when natural infection occurs during pregnancy 1. Women should avoid becoming pregnant for at least 28 days after receiving the MMR vaccine. However, if a pregnant woman inadvertently receives the MMR vaccine, this is not typically considered a reason to terminate the pregnancy, as no cases of congenital rubella syndrome have been documented following vaccination during pregnancy 1. The theoretical risk must be weighed against the actual risk of natural infection.
Some key points to consider:
- The MMR vaccine contains live attenuated viruses that could potentially cross the placenta and affect the fetus 1.
- Women who are planning pregnancy should ensure they are immune to measles, mumps, and rubella before conception, either through prior vaccination or natural infection 1.
- If a non-immune woman requires vaccination, it should be administered at least 28 days before attempting conception to eliminate any potential risk to the fetus 1.
- The estimated risk for serious malformations to fetuses attributable to the mother receiving RA 27/3 vaccine is considered to range from zero to 1.6% 1.
- Evidence does not support a link between MMR vaccination and any of the following: hearing loss, retinopathy, optic neuritis, Guillain-Barré Syndrome, type 1 diabetes, Crohn’s disease, or autism 1.
In terms of counseling, women who receive the MMR vaccine should be advised to avoid becoming pregnant for 28 days after vaccination, and those who are pregnant or become pregnant within 28 days of vaccination should be counseled about the theoretical risks to the fetus 1. However, termination of pregnancy is not typically recommended due to the low risk of congenital rubella syndrome from vaccination 1.
From the Research
Risks of the MMR Vaccine to Pregnant Patients
- The MMR vaccine is a live vaccine, which is generally contraindicated during pregnancy due to the risk of fetal viremia/bacteremia 2, 3, 4.
- The MMR vaccine should be offered to women during pre-pregnancy counseling, with advice to avoid pregnancy for a month after vaccination 2.
- There is no evidence that the MMR vaccine causes increased risks of malformations, congenital rubella syndrome, or other adverse pregnancy outcomes 4.
- However, the theoretical concerns about live vaccines during pregnancy lead to recommendations against their use in pregnant women 3, 5, 4.
General Recommendations for Vaccines During Pregnancy
- Inactivated vaccines, such as tetanus toxoid and flu vaccines, are generally considered safe during pregnancy 2, 3, 4.
- The decision to vaccinate a pregnant woman should balance the risk of exposure to disease against the potential risks of vaccination 3, 6.
- Vaccination during pregnancy is important for protecting both the mother and the fetus from infectious diseases 2, 6.
- Healthcare providers should be familiar with current recommendations for vaccinations during pregnancy to provide optimal care 6.