Some important facts of measles mumps and rubella vaccine

What is the measles, mumps, and rubella (MMR) vaccine?

The MMR vaccine is a mixture of live but weakened measles, mumps, and rubella viruses. The vaccine helps the body build antibodies to these viruses and protects against these viruses in the future. These antibodies usually last for life. In the U.S. the MMR vaccine is usually given during childhood in two doses.

I am not sure if I ever had the MMR vaccine. Should I get the vaccine before getting pregnant?

It is recommended that all people of childbearing age who do not have immunity to measles, mumps, and rubella receive the MMR vaccine at least one month before getting pregnant. If you were born outside the U.S., or are not sure if you were vaccinated, your healthcare provider can do a blood test to see if you have antibodies to these viruses.

I just got an MMR vaccine. How long should I wait until I get pregnant?

The Centers for Disease Control and Prevention (CDC) suggests waiting to get pregnant, if possible, until one month after receiving the MMR vaccine and your immunity is confirmed by a blood test.

Does getting the MMR vaccine increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if the MMR vaccine can increase the chance of miscarriage. Infection with measles, mumps, and/or rubella during pregnancy may increase the chance of miscarriage.

Does getting the MMR vaccine increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. There is no evidence to suggest that getting the MMR vaccine during pregnancy increases the chance of birth defects. Information from at least 1,600 pregnancies in which the MMR vaccine was given right before or during pregnancy found no increased chance of birth defects.

The MMR vaccine is not recommended during pregnancy because of a very small chance of illness from the weakened viruses in the vaccine itself. This is very rare in the general population, and there has never been a documented case of CRS from the MMR vaccine.

Does getting the MMR vaccine increase the chance of other pregnancy-related problems?

it is not known if the MMR vaccine can cause other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). Because the MMR vaccine is not recommended for use during pregnancy, vaccination in the second and third trimester has not been well studied.

Will getting the MMR vaccine during pregnancy affect future behavior or learning for the child?

This has not been well studied. Based on the available data, getting the MMR vaccine during pregnancy is not expected to cause behavior or learning issues for the child.

Breastfeeding and getting the MMR vaccine:

The MMR vaccine can be given to people who are breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions.

If a male gets the MMR vaccine, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?

Studies have not been done to see if the MMR vaccine could affect male fertility or increase the chance of birth defects above the background risk. When a male gets vaccinated, this can help protect his partner, a pregnancy, and children from getting infected with these illnesses. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy