Rubella Immunity Test Before Pregnancy: What to Know

What does the evidence say about rubella immunity test before pregnancy during pregnancy?

1. A blood test can check whether you have protective antibodies to rubella, and clinicians recommend that anyone of childbearing age without documented immunity get the MMR vaccine at least one month before trying to become pregnant. 1
2. In one study using a standard threshold of rubella IgG above 10.0 IU per milliliter as the marker of protective immunity, about 1 in 10 women tested came back seronegative, meaning their antibody level had dropped below the protective threshold despite a history of vaccination. 2
3. Rubella infection early in pregnancy carries the highest risk to the baby: transmission across the placenta can reach up to 90% in the first 12 weeks, with the most severe structural problems concentrated in infections during the first eight weeks. 3
4. Because rubella infection during pregnancy can lead to pregnancy loss or birth defects in a surviving baby, researchers recommend routine rubella screening in prenatal care so any needed follow-up happens early. 4
5. For women of childbearing age found to be seronegative, guidance suggests a repeat vaccine dose should be considered when antibody levels are non-protective, since immunity from an earlier vaccination can wane over time. 2

Is rubella immunity test before pregnancy safe in each trimester?

• First trimester. Before you start trying, this is an easy blood test to add to a preconception visit, since results take time to come back and, if you need the MMR vaccine, you'll need to wait a month before conceiving anyway.
• Second trimester. If you haven't been tested yet and you're already trying, ask your provider about checking now rather than waiting, since a non-immune result means a vaccine and a one-month waiting period before continuing to try.
• Third trimester. If you know you're not immune and can't fit in the MMR vaccine before conceiving, tell your prenatal team as soon as you're pregnant, since the vaccine itself isn't given during pregnancy and extra precautions around rubella exposure become more important.