Can measles infection during pregnancy cause birth defects?

Measles Infection During Pregnancy and Birth Defects

Unlike rubella, measles infection during pregnancy is not associated with congenital defects or a specific pattern of birth malformations. 1, 2

Measles vs. Rubella in Pregnancy

Measles (Rubeola)

• No evidence of congenital defects: Current evidence does not support an association between measles infection during pregnancy and congenital malformations 2
• Maternal and pregnancy complications: Measles during pregnancy is associated with:
  • Increased maternal morbidity and mortality (particularly respiratory complications) 3
  • Higher rates of premature labor 2, 4
  • Spontaneous abortion and fetal loss 2
  • Low birth weight 2
  • Perinatal infection if occurring in late pregnancy 5

Rubella (German Measles)

• Significant teratogenic effects: Rubella is well-documented to cause Congenital Rubella Syndrome (CRS) 1
• Risk by gestational age:
  • First 8 weeks: 85% risk of fetal defects 1
  • 9-12 weeks: 52% risk of defects 1
  • First 20 weeks: 20-25% overall risk (likely underestimated) 1
  • After 20 weeks: Rarely causes defects 1
• Congenital anomalies include:
  • Auditory: Sensorineural deafness
  • Ophthalmic: Cataracts, microphthalmia, glaucoma, chorioretinitis
  • Cardiac: Patent ductus arteriosus, peripheral pulmonary artery stenosis, septal defects
  • Neurologic: Microcephaly, meningoencephalitis, mental retardation
  • Growth: Both intrauterine and postnatal growth retardation 1

Prevention and Management

For Measles

• Post-exposure prophylaxis: Human normal immunoglobulin for susceptible pregnant women exposed to measles 2, 3
• Monitoring: Daily fetal monitoring for 14 days following eruption if the fetus is viable 4
• Symptomatic treatment: Including tocolysis if preterm labor occurs 4

For Rubella

• Pre-pregnancy vaccination: All women of childbearing age should be evaluated for MMR immunity before pregnancy 6
• Pregnancy screening: Prenatal screening for rubella immunity is indicated for all pregnant women 6
• Post-partum vaccination: Non-immune women should be vaccinated immediately after delivery 6

Important Considerations

• Vaccination timing: Women should avoid pregnancy for 3 months after receiving MMR vaccine 6
• Accidental vaccination during pregnancy:
  • No cases of congenital rubella syndrome have been observed in infants born to mothers who received MMR during pregnancy 6
  • Termination of pregnancy is NOT recommended based on MMR vaccination alone 6
  • The estimated risk from the vaccine (0-1.6%) is substantially lower than the ≥20% risk from natural rubella infection 1, 6

Clinical Pitfalls to Avoid

• Don't confuse measles and rubella: They have different implications for pregnancy outcomes
• Don't assume immunity: About 15% of women of childbearing age remain susceptible to rubella 7
• Don't delay post-exposure prophylaxis: For measles exposure, immunoglobulin should be administered within 6 days 4
• Don't vaccinate during pregnancy: MMR is contraindicated during pregnancy, but should be given immediately postpartum if needed 6
• Don't delay breastfeeding: Breastfeeding is NOT a contraindication to MMR vaccination 6

Remember that while measles can cause severe maternal and pregnancy complications, it does not cause the pattern of birth defects associated with Congenital Rubella Syndrome.