(Reaffirmed April 2021)
This Practice Advisory was developed by the American College of Obstetricians and Gynecologists’ Immunization, Infectious Disease, and Public Health Preparedness Expert Work Group with Linda O’Neal Eckert, MD and Laura E. Riley, MD in collaboration with Alisa Kachikis, MD and the University of Washington.
The United States is currently experiencing the greatest number of reported cases of measles, also known as rubeola, since the disease was eliminated in 2000 1. Outbreaks have been confirmed in 22 states and the number of cases and their distribution is increasing rapidly. These measles outbreaks have been linked to travelers bringing back cases of measles from other countries. This situation combined with low vaccination coverage among certain communities in the United States leads to pockets of vulnerable communities and contributes to outbreaks such as the one we are currently experiencing.
Measles is highly contagious. An estimated 92-95% of individuals in a community must be immune to prevent ongoing transmission. Measles can cause serious illness and infects approximately nine out of every ten susceptible individuals exposed in close-contact settings 2. Anyone who is unvaccinated or is undervaccinated is at risk. Certain individuals, including unvaccinated and undervaccinated pregnant women, infants 12 months of age or younger, and severely immunocompromised persons are at increased risk of severe illness and complications of measles 2. The two-dose series of the measles-mumps-rubella (MMR) vaccine is safe and is 97% effective at preventing measles infection 2.
Measles Infection during Pregnancy
Measles infection in pregnant women is associated with several adverse events including increased risk of hospitalization and pneumonia 3. Measles infection during pregnancy is also associated with significant risks to the fetus 4 5 6, including:
- Low birth weight
- Increased risk of preterm delivery
The University of Washington has developed a consensus statement including algorithms for guidance in managing high risk pregnant patients—those living in, or traveling to, areas with an active outbreak. Providers who care for pregnant women are encouraged to refer to the recommendations and algorithms in this ACOG-Supported consensus statement for additional information 7.
Selected points from the ACOG-supported University of Washington consensus statement, ACOG, and the Centers for Disease Control and Prevention (CDC) are highlighted below.
Women Considering Pregnancy
- Women of reproductive age and those contemplating pregnancy should assess their measles immune status with their primary health provider prior to pregnancy 7 (see algorithm) and receive the measles-mumps-rubella (MMR) vaccine if nonimmune*.
- After receiving the MMR vaccine, women should wait 4 weeks prior to attempting pregnancy given theoretical risks to the fetus with live vaccines; however, inadvertent MMR vaccination in the periconception period or in early pregnancy should not be considered an indication for termination of pregnancy 4.
- One documented dose of MMR vaccine is sufficient for low risk individuals (including pregnant women). For people at high risk of contracting measles, a documented history of two prior MMR vaccine doses is needed to confirm immunity. However, obstetrician-gynecologists should consult their local health departments when determining immunity from vaccination (e.g. number of doses necessary).
- In areas of ongoing outbreaks where there is sustained transmission in close-knit communities, serologic testing for measles IgG can be considered in pregnant women without documented immunity to measles.
- Pregnant women with suspected measles exposure but without immunity should receive intravenous immunoglobulin (IGIV) treatment 2 4 7 within 6 days of measles exposure.
- If serologic testing and obtaining results are not available in a timely manner, and measles exposure is suspected in a non-immune pregnant woman, the patient should receive measles immunoglobulin (IGIV).
- While most women have immunity to measles due to prior MMR vaccination, given risks associated with measles in pregnancy, possible infection or exposure to measles should be carefully and expediently investigated 2. Obstetrician-gynecologists should follow local health department guidance for testing (see algorithm in reference 7).
- MMR vaccine should be administered postpartum* to women who lack evidence of measles immunity.
Addressing Vaccination With Your Patients
- Parental choice to opt-out of infant and childhood vaccination allows population immunity to drop below the threshold levels needed to stop outbreaks of measles, placing vulnerable patients such as pregnant women, infants under 12 months of age, and immunocompromised individuals at increased risk.
- During prenatal visits, discuss the importance of vaccination, especially measles, with your patients and encourage them to vaccinate their children.
- Most women start the decision-making process about vaccinations for their children before or during pregnancy. This is especially important for first-time parents who tend to be more vaccine hesitant 10.
- A randomized control trial showed that prenatal or postnatal education of mothers on childhood vaccinations resulted in higher infant immunization rates 11.
ACOG will continue to provide updates as available while these outbreaks progress. For additional information please check the Centers for Disease Control and Prevention’s Measles Cases and Outbreaks webpage, along with the ACOG-Supported University of Washington’s Obstetric Consensus Statement: Measles & the MMR Vaccine: Recommendations Around Pregnancy, Including the Periconception and Postpartum Periods.
*Live vaccines, such as MMR, are not recommended during pregnancy due to theoretical risks to the mother and fetus; however, adverse effects on fetuses when live vaccines are inadvertently administered during pregnancy have not been found to occur.