What we know about measles during pregnancy

The recent death of an Ontario infant born prematurely and infected with measles through the mother has raised questions about how the virus is transmitted during pregnancy. The tragic incident was the first fatality in the provincial outbreak that began on Oct. 28 last year and includes 2,009 probable and confirmed cases.

Dr. Kieran Moore, Ontario’s chief medical officer of health, stated that while measles may have been a contributing factor in both the premature birth and death of the infant, the baby also faced other serious medical complications unrelated to the virus. Measles is a respiratory infection with symptoms that include fever, a blotchy rash, a cough, and red, watery eyes. In May 2024, a child under five died of measles in Hamilton, marking the first measles-related death in the province in more than a decade.

The current outbreak was traced back to a Mennonite wedding in New Brunswick and is primarily spreading in Mennonite and Amish communities where vaccination rates are low. The majority of cases are located in southwestern Ontario.

Dr. Jacqueline Wong, a pediatric infectious diseases specialist at McMaster Children’s Hospital, mentioned that transmission of measles during pregnancy is rare. The impact of the virus on the baby varies depending on the trimester of pregnancy, as factors like fetal development, placenta development, and blood flow play a role.

Pregnant individuals infected with measles face serious complications, including an increased risk of lung infections like pneumonia and a higher likelihood of miscarriage or premature birth. Babies born to mothers infected with measles can experience complications related to premature birth, such as low birth weight and breathing issues, in addition to the symptoms of the virus itself.

The measles vaccine, known as the Measles, Mumps, and Rubella (MMR) vaccine, has been safely used for over 50 years and is highly effective. Two doses provide nearly 100% protection against the virus. Health officials stress the importance of vaccination for everyone, especially those who may become pregnant.

It is not recommended to administer the measles vaccine to individuals who are already pregnant due to the live strain of the virus contained in the vaccine. Instead, vaccines that contain inactivated viruses, such as the flu vaccine, can be given during pregnancy.

In the event of measles exposure during pregnancy, health officials advise contacting the local health authority for appropriate care. Injectable medication options like IVIg may be used to protect against infection or reduce the severity of the illness. However, the best way to protect against measles is through immunization.

In conclusion, ensuring that individuals are up to date with all immunizations before pregnancy is crucial in preventing the transmission of measles and other infectious diseases. It is essential to prioritize vaccination to protect both the parent and the baby from potential health risks associated with measles infection during pregnancy.