MMR Vaccination Before Pregnancy
All women of childbearing age without documented immunity to rubella should receive MMR vaccine before conception, and must avoid pregnancy for 3 months after vaccination. 1
Who Needs Pre-Pregnancy MMR Vaccination
Women without acceptable evidence of immunity require vaccination. Acceptable evidence includes:
- Laboratory confirmation of rubella immunity 1
- Documentation of at least one dose of rubella-containing vaccine given on or after the first birthday 2, 3
- Birth before 1957 does NOT count as acceptable evidence for women who can become pregnant 2, 3
Do not rely on self-reported vaccination history or parental reports—these are inadequate documentation. 3
Critical Timing: The 3-Month Rule
Women must avoid pregnancy for 3 months after MMR vaccination. 2, 1 This precautionary measure exists because MMR contains live attenuated virus that theoretically could cross the placenta. 1
The actual risk is negligible. Among 321 rubella-susceptible pregnant women inadvertently vaccinated within 3 months of conception, zero infants had malformations compatible with congenital rubella syndrome, with an estimated risk of 0% to 1.6% (95% confidence interval). 1 Additional data from mass campaigns involving 2,894 susceptible pregnant women who received rubella vaccine showed no cases of CRS among 1,980 live births. 4
When and Where to Vaccinate
Offer MMR vaccination during any healthcare encounter: 2, 1
- Routine medical and gynecologic visits
- Family planning visits
- Premarital evaluation
- When children undergo routine examinations or vaccinations
- Before discharge from hospitals for any reason (if not pregnant)
Vaccinate immediately without serologic testing when: 2, 3
- Costs of serology are high
- Follow-up of identified susceptible women for vaccination cannot be assured
- The woman states she is not pregnant
Special Populations Requiring Attention
Women born outside the United States, particularly those of Hispanic ethnicity, require special outreach. 2, 1 Recent rubella outbreaks have occurred in these populations who may have grown up in areas without routine rubella vaccination.
If Pregnancy Occurs Before Vaccination
MMR is absolutely contraindicated during pregnancy. 2, 1, 5, 6
If a woman is already pregnant:
- Screen for rubella antibodies prenatally 1, 5
- Vaccinate immediately postpartum before hospital discharge 2, 1, 5
- Postpartum vaccination could prevent 40-50% of CRS cases in future pregnancies 1, 5
- Breastfeeding is NOT a contraindication to postpartum MMR vaccination 1, 5
Why This Matters
Rubella infection during the first trimester carries up to 85% risk of devastating fetal malformations including deafness, cardiac defects, cataracts, and mental retardation. 1, 5 The benefit of preventing congenital rubella syndrome far outweighs the theoretical vaccine risk. 1
Counseling Points
When counseling women about pre-pregnancy MMR vaccination:
- Explain the theoretical fetal risk 2, 1
- Emphasize the requirement to avoid pregnancy for 3 months after vaccination 2, 1
- Reassure that inadvertent vaccination during early pregnancy should not be a reason to consider termination of pregnancy 2
- If inadvertent vaccination occurs, counsel about the theoretical basis of concern but emphasize the actual risk is negligible 2, 4