What are the MMR (Measles, Mumps, Rubella) vaccination recommendations for pregnant women?

MMR Vaccination Recommendations for Pregnant Women

MMR (Measles, Mumps, Rubella) vaccine is contraindicated during pregnancy due to the theoretical risk to the fetus, as it contains live attenuated viruses. 1, 2

Key Recommendations

Before Pregnancy

• All women of childbearing age should be evaluated for MMR immunity before pregnancy
• Women who are not immune should receive MMR vaccination before conception
• Women should avoid pregnancy for 3 months after receiving MMR vaccine 1

During Pregnancy

• Pregnant women should NOT receive MMR vaccine regardless of their immune status 1
• Prenatal screening for rubella immunity is indicated for all pregnant women who lack acceptable evidence of immunity 1
• If a pregnant woman is inadvertently vaccinated:
  • She should be counseled about the theoretical risk to the fetus
  • Termination of pregnancy is NOT recommended based on MMR vaccination alone 1
  • No cases of congenital rubella syndrome or abnormalities attributable to vaccine virus have been observed in infants born to mothers who received MMR during pregnancy 1

After Pregnancy

• Women who do not have evidence of rubella immunity should be vaccinated with MMR immediately after delivery, before discharge from the hospital, birthing center, or abortion clinic 1
• Postpartum vaccination of non-immune women could prevent up to half of Congenital Rubella Syndrome cases 1
• Women should be counseled to avoid pregnancy for 3 months following vaccination 1

Evidence on Safety

Despite theoretical concerns, the safety profile of inadvertent MMR vaccination during pregnancy is reassuring:

• From 1971-1989, CDC followed 321 rubella-susceptible pregnant women who received rubella vaccine during or around conception
• None of the 324 infants born to these mothers had malformations compatible with congenital rubella infection 1
• The estimated risk for serious malformations attributable to RA 27/3 rubella vaccine (currently used in the US) ranges from zero to 1.6% 1
• This is substantially less than the ≥20% risk for Congenital Rubella Syndrome associated with natural rubella infection during first trimester 1

Special Considerations

Breastfeeding

• Breastfeeding is NOT a contraindication to MMR vaccination 1
• Although vaccine virus can be excreted in breast milk, any infection in the infant remains asymptomatic 1

Healthcare Workers

• Female healthcare workers born before 1957 who can become pregnant should have laboratory evidence of rubella immunity or receive vaccination 1
• Pregnant healthcare workers should not receive MMR vaccine until after delivery 1

Common Pitfalls to Avoid

1. Delaying postpartum vaccination: Ensure vaccination occurs before hospital discharge to maximize protection
2. Ignoring immune status: All pregnant women without documented immunity should be screened
3. Recommending pregnancy termination after accidental vaccination: This is not supported by evidence
4. Assuming birth year guarantees immunity: Birth before 1957 is not acceptable evidence of immunity for women who could become pregnant 1
5. Delaying vaccination due to anti-Rho(D) immune globulin: Postpartum MMR vaccination should not be delayed because anti-Rho(D) or other blood products were received 1

In summary, while MMR vaccination is contraindicated during pregnancy, it should be administered to non-immune women immediately postpartum. If accidental vaccination occurs during pregnancy, the woman should be reassured that available evidence does not support an increased risk of congenital abnormalities.