Measles exposure during pregnancy

By trimester

Weeks 1–13

1st trimester

Measles is not linked to birth defects the way some other infections are, but early pregnancy loss has been reported after infection, and a fever this high always deserves prompt attention. If you have not had the MMR vaccine and were around someone with measles, call your provider the same day you find out.

Weeks 14–27

2nd trimester

The breathing complications that make measles harder on pregnant people, including pneumonia, are a real concern here since lung capacity is already more limited. Preterm labor is a documented risk with measles infection at this stage, so contractions or fluid leaking after a measles exposure or illness deserve the same urgency as any other preterm labor sign.

Weeks 28–birth

3rd trimester

Timing close to delivery adds a newborn consideration on top of the maternal one: a baby born during or shortly after a parent's measles illness can be born with the infection itself. Preterm delivery is also more common with measles in pregnancy than in the general population, so this is not a fever to wait out at home.

What does the evidence show for measles exposure?

• In one outbreak-year study, pregnant women with measles had a 25 percent preterm delivery rate compared with the usual 5 to 15 percent, and 21 percent developed a respiratory complication like pneumonia versus 9 percent of nonpregnant women infected in the same outbreak. 1
• Post-exposure immune globulin can ease the course of measles if given quickly: guidance for pregnant people without immunity calls for 1 gram within 72 hours, and no later than 6 days, after contact with someone infectious. 1
• Measles itself is not expected to raise the chance of birth defects, but infection in a pregnant person without immunity is tied to a higher chance of preterm delivery, low birth weight, and possibly stillbirth. 2
• The MMR vaccine is a live-virus vaccine and is not recommended during pregnancy, though research following over 1,600 pregnancies exposed to the vaccine has not found a higher chance of birth defects, and it is fine to receive while breastfeeding. 3
• Anyone planning a pregnancy who is not already immune should get the MMR vaccine at least one month before trying to conceive, since waiting confirms the vaccine's weakened viruses have cleared before conception. 4

When should I call my provider about measles exposure?

Measles starts with fever, cough, runny nose, and red watery eyes days before the rash itself appears, and a person is contagious from about 4 days before the rash shows up until 4 days after it fades. Any fever during pregnancy is worth a call to your provider, and a measles-pattern rash, breathing trouble, or a fever that will not come down needs same-day evaluation rather than home monitoring. Because post-exposure immune globulin only works within a 6-day window, the most time-sensitive action is calling your provider the same day you learn about an exposure, before any symptoms even start. Whatever the pattern, any symptom that feels beyond your usual range is a reason to call: obstetric teams expect these questions and would rather hear early than late.