What we know about measles during pregnancy

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Health

The decease of an Ontario babe who contracted measles portion successful the womb and was past calved premature is raising questions astir the microorganism and however it effects pregnancy.

Doctors impulse vaccination pursuing decease of Ontario babe infected with measles successful the womb

Amina Zafar · CBC News

· Posted: Jun 05, 2025 9:58 PM EDT | Last Updated: June 6

A large   idiosyncratic   holds their stomach

After the decease of an Ontario babe who contracted measles successful the womb, wellness officials successful the state are uring everyone, particularly those who whitethorn go pregnant, to guarantee they are up to day connected their immunizations. (LM Otero/The Canadian Press)

The decease of an Ontario babe calved prematurely and infected with measles done the parent is raising questions astir however the microorganism is transmitted during pregnancy.

On Thursday, Ontario health officials announced the decease of a babe who was infected with the microorganism portion successful the womb. It was the archetypal fatality successful the provincial outbreak that began connected Oct. 28 past twelvemonth and includes 2,009 probable and confirmed cases.

"While measles whitethorn person been a contributing origin successful some the premature commencement and death, the babe besides faced different superior aesculapian complications unrelated to the virus," Dr. Kieran Moore, Ontario's main aesculapian serviceman of health, said successful a connection released Thursday. 

Measles is simply a respiratory corruption with symptoms that include fever, a blotchy rash, a cough and red, watery eyes. In May 2024, a kid nether five died of measles successful Hamilton, but earlier that, determination were no measles deaths successful the state successful much than a decade.

Moore has antecedently said the existent outbreak was traced to a Mennonite wedding successful New Brunswick, and is spreading chiefly successful Mennonite and Amish communities wherever vaccination rates lag. The bulk of those cases are successful southwestern Ontario.

WATCH | Death of a measles-infected babe successful Ontario: 

Measles-infected babe dies successful southwestern Ontario

An babe calved prematurely and infected with measles successful the womb done their parent has died, Ontario's Chief Medical Officer Dr. Kieran Moore announced Thursday. It is the province's archetypal recorded decease from the existent outbreak that started successful October of past year.

Health officials accent that anyone who isn't vaccinated is susceptible to measles and they encourage everyone to guarantee they are up to day connected their Measles, Mumps and Rubella (MMR) vaccines. 

"I impulse everyone, but particularly those who whitethorn go pregnant, to guarantee they person received 2 doses of the MMR vaccine, which volition support some a genitor and baby," said Moore.

What is known astir measles transmission during pregnancy?

Dr. Jacqueline Wong, a pediatric infectious diseases specializer astatine McMaster Children's Hospital, says transmission of measles during gestation is rare.

If the babe does declaration measles from the parent successful utero, Wong says the interaction varies depending connected however acold on the gestation is. 

"Your hazard of transmitting the infection to the babe varies during the antithetic trimesters due to the fact that of the improvement of the fetus, the improvement of the placenta and the humor flow."

What are the risks during pregnancy?

Dr. Sheryl Choo, a maternal-fetal medicine specializer astatine Royal Alexandra Hospital successful Edmonton, says there are superior complications that tin effect if radical who are large go infected with measles. 

For instance, she says large radical infected with measles tin make lung infections similar pneumonia astatine astir treble the complaint of those who are not pregnant. 

Vials of the MMR measles mums and rubella microorganism  vaccine successful  Texas successful  2025.

Anyone who isn't vaccinated with 2 doses of the measles, mumps and rubella vaccine is susceptible to measles, wellness officials say. They accent that the vaccine has been safely utilized for implicit 50 years and is highly effective. (Julio Cortez/The Associated Press)

If radical go infected with measles during pregnancy, Choo notes it tin besides summation the hazard of superior complications including miscarriage and premature birth.

According to Moore, the MMR vaccine has been safely utilized for implicit 50 years and is highly effective. "Two doses supply astir 100 per cent protection," helium said successful a connection Thursday.

What astir risks to the baby?

Babies calved to those infected with measles can face complications related to premature birth, specified arsenic debased commencement value and breathing issues, which tin effect in stays successful the neonatal intensive attraction unit, Choo said. 

This is each connected apical of the symptoms of a measles infection itself, she said. 

Much rarer complications of measles tin see subacute sclerosing panencephalitis, oregon SSPE. It is astir ever fatal and mostly develops 7 to 10 years aft an archetypal measles infection, adjacent if the idiosyncratic appears to person afloat recovered. 

It tin beryllium dormant successful the encephalon for years and may yet flare up, causing encephalon inflammation and resulting successful children oregon young adults losing the quality to determination and speak.

According to the Public Health Agency of Canada, SSPE occurs successful betwixt 4 and 11 retired of each 100,000 measles cases.

Health officials say the highest rates are among children who declaration measles earlier the property of two.

If I'm large tin I get the measles vaccine?

No, the measles vaccine is not recommended to be administered to radical who are already pregnant. 

"If you privation to instrumentality the measles vaccine, it has to beryllium earlier you're pregnant," Choo said.

That's due to the fact that the measles vaccine contains a unrecorded strain that is simply a weakened signifier of the virus, which is not recommended during pregnancy. 

Choo says that's because determination is simply a theoretical hazard that the measles microorganism contained successful the vaccine tin beryllium passed to the baby.  

In contrast, vaccines that contain inactivated viruses can beryllium fixed during pregnancy. The flu vaccine is 1 example.

Is determination attraction for pregnant people exposed to measles?

If you're large and you deliberation you whitethorn person been exposed to measles, wellness officials counsel you to interaction your section wellness authority. They tin find if vulnerability occurred and nonstop patients to seek appropriate attraction without contributing to further spread.

If measles vulnerability is confirmed, Choo says determination is an injectable medicine enactment called IVIg. Depending connected erstwhile the vulnerability occurred, the medicine may be utilized to assistance support against corruption oregon trim severity of the illness. 

However, wellness officials and doctors hold that the champion mode to support against measles is immunization. 

"The astir important proposal oregon proposal I tin springiness … is to marque definite you're up to day with each the immunization if you're starting that travel of becoming pregnant," Wong said.

ABOUT THE AUTHOR

Amina Zafar covers aesculapian sciences and wellness attraction for CBC. She contributes to CBC Health's Second Opinion, which won metallic for champion editorial newsletter astatine the 2024 Digital Publishing Awards. She holds an undergraduate grade successful biology subject and a master's successful journalism.

    With files from CBC's Alison Northcott and Christine Birak

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