A health care specialist is advising pregnant women to stay away from hot yoga to avoid possible prenatal abnormalities. His warning comes after a pregnant woman was kicked out of a popular London Ont. yoga studio.

"That level of heat and humidity may not be safe for the developing fetal brain in the second and third trimester and the entire developing fetus in the first trimester," said Dr. Gregory Davies, the chair of Maternal-Fetal Medicine at Queen's University.

"We have lots of theoretic concerns why it would be unsafe and we have no evidence to say it is safe," said Davies, who clarified that current research is based off of animal models

Dr. Gregory Davies

A health care specialist is advising expecting mothers to stay away from hot yoga to avoid possible prenatal abnormalities after a pregnant woman was kicked out of a popular London Ont. yoga studio. (Submitted by Queen's University.)

His comments come after a pregnant London woman spoke out after being told by an instructor that hot yoga wasn't safe. The woman said she was given a green light by her own midwife to attend the classes.

Davies, who has studied exercise and pregnancy for more than two decades, said the studio did the right thing — as prenatal concerns begin after a pregnant woman's core body temperature rises, similar to the way it would if a woman had a fever.

"I am certain that every hot yoga studio would react in the same way that this [one] did," he said. "Although a woman may choose to take those risks on herself, that doesn't mean that the proprietor of the hot yoga studio has to take those risks on as well."

Risk factors

Davies said possible complications for pregnant women could begin after their average body temperature exceeds 37 degrees — as it could at a hot yoga class or in a hot tub.

In the first trimester, warmer body temperatures could increase the possibility of congenital abnormalities in the developing fetus as the organs are still forming. More specifically, an unborn baby may be prone to developing Spina Bifida, which is related to incomplete development of the spinal cord.

In the second and third trimester, a healthy growing fetus would already have developed organs, excluding the brain. Therefore, warmer temperatures may hinder the ability for the brain to develop normally.

Hayley Ross

Hayley Ross is due to give birth Jan. 5. She was asked to leave a hot yoga class at Yoga Shack in London because she's pregnant. (Supplied photo)

Prenatal exercise

Davies recommends pregnant women exercise in mild environments such as at a traditional yoga studio or a gym, on stationary bikes or treadmills.

"Exercise in pregnancy is a very healthy part of pregnancy. Yoga is a wonderful exercise to deal with the aches and pains that come with the third trimester to stretch out your back and hips and your pelvis. It's an absolutely wonderful thing to do – just not in a hot environment," he said.