SMFM: Measles Exposure in Pregnant Women

Yesterday, the Society for Maternal-Fetal Medicine (SMFM) released recommendations in response to the recent measles outbreak. The primary recommendation is that the measles, mumps, and rubella (MMR) vaccine should not be administered during pregnancy and can only be given postpartum.

The current measles outbreak involves 14 states, with 102 people having been sickened from January 1, 2015, to January 30, 2015. While the California cases have caused a wave of media coverage, the CDC actually reports that 2014 saw a record number of 644 cases of measles in 27 states. According to the CDC’s National Center for Immunization and Respiratory Diseases, this is the greatest number of cases reported since the disease was considered eliminated in 2000.

The measles vaccine was first introduced in the United States in 1963. Before 1989, Federal guidelines recommended only one dose of the measles vaccine. Currently, two doses of the vaccine (MMR) are recommended, so people vaccinated before the guidelines changed in 1989 do not have the coverage that’s now advised. There’s a 5% chance of vaccine failure in people who receive only one shot. The chance of failure drops to less than 1% for those who get two doses.

Neil S. Silverman, MD, a member of the SMFM Board of Directors affiliated with the Center for Fetal Medicine & Women’s Ultrasound in Los Angeles and the UCLA/David Geffen School of Medicine in Los Angeles, who is also an Ob/Gyn infectious disease specialist, made the following recommendations for women who are pregnant or trying to become pregnant:

- Measles is dangerous to the health of both mothers and their unborn children. Pregnant women who contract measles are at risk for more severe complications of the illness, as well as at increased risk for both preterm labor and preterm delivery.

- Women who are trying to become pregnant should consider getting the measles vaccine again if they have not had two doses. Revaccination will depend on when you received the initial vaccine. When the vaccine was created 40 to 50 years ago, the immune systems of immunized people had to regularly fight off the measles virus. Now that the virus is rare, some people who were vaccinated in the 1960s to 1980s may be more susceptible today.

- For pregnant women, MMR can only be given postpartum. It is safe to breastfeed after receiving the vaccine. Other women should be vaccinated before pregnancy if they have not had two past immunizations.

- If there’s a question about vaccination, a measles antibody test can be ordered. Despite the fact that both measles (rubeola) and German measles (rubella) are covered in the MMR vaccine, immunity needs to be ordered separately. (No separate vaccine for measles alone exists any more.)

- If patients born after 1963 are immune to rubella (German measles), they usually also will be immune to measles. However, it’s safest to check if there’s a question about immunity. If there’s uncertainty or lack of documentation about a patient having received a second MMR vaccine, it’s best to vaccinate. There’s no danger or risk if a person receives a third shot if it turns out that they received two shots in the past.

“If you’re pregnant and not immune to measles or uncertain about your immunity or immunization status, you should be cautious about exposure to large crowds, especially those where there are international tourists such as theme parks, museums, and airports,” Silverman explained. “Pregnant women who are not immune to measles should also avoid contact with children who have not been immunized. We also encourage all families to vaccinate their children against measles and other vaccine-preventable illnesses.”

“If you live in an area where a measles outbreak has been reported, you can also get a measles antibody test for peace of mind,” Silverman added.

(From a Society for Maternal-Fetal Medicine press release.)