Pubdate: Mon, 14 Aug 2017
Source: Globe and Mail (Canada)
Copyright: 2017 The Globe and Mail Company
Contact:  http://www.theglobeandmail.com/
Details: http://www.mapinc.org/media/168
Author: Paul Taylor
Page: L1

WILL SMOKING MARIJUANA DURING PREGNANCY HARM THE CHILD?

THE QUESTION

My daughter is pregnant and she has been smoking some marijuana to
reduce nausea and vomiting from morning sickness. She says marijuana
is a natural product and it won't hurt her unborn child. Is she right?

THE ANSWER

There is no evidence that marijuana causes obvious birth defects. And
this fact may be contributing to the impression that it's safe to use
during pregnancy.

But "it is not a benign substance," warns Dr. Erin Lurie, a fellow in
addictions medicine at the Centre for Addiction and Mental Health in
Toronto.

A growing body of research suggests exposure to marijuana in the womb
has other, more subtle, effects - especially on the developing brain.
In a nutshell, it may increase the baby's risk of learning
difficulties, impulsiveness and inattention, as well as other
behavioural and mental health problems later in life.

Separate research teams in Ottawa and Pittsburgh have carried out the
longest-running studies on the children of women who smoked cannabis
during pregnancy.

The Ottawa study began in 1978, with the recruitment of about 600
pregnant women mostly from middle-class backgrounds. Some of the women
had smoked marijuana; others smoked tobacco; still others used
marijuana and tobacco; the rest abstained from both substances.

The amount of marijuana consumed and the duration of use varied from
woman to woman. Their offspring have undergone extensive testing at
regular intervals into adulthood. A select sample from the offspring
continue to be followed up.

The Pittsburgh study started in 1982, and also included about 600
mothers, although most were from low-income backgrounds.

Both these studies, plus other research, point to the same
conclusions. "I think the similar results lend a lot of credence to
our findings," says the lead researcher of the Ottawa study, Peter
Fried, professor emeritus in the department of psychology at Carleton
University.

In particular, the studies indicate that marijuana affects certain
aspects of executive functioning, which primarily take place in the
brain's prefrontal cortex.

Executive functioning "enables you to make decisions and anticipate
the consequences of your actions," Fried explains.

Marijuana also impairs attention and visual problem solving - for
example, doing something as ordinary as a jigsaw puzzle.

As well, "the lack of sustained attention usually means they can't
inhibit themselves from doing other things." This can translate into
impulsive behaviour.

Fried says some of the effects of marijuana exposure are not
immediately apparent in newborns. It wasn't until the children were
four years old that cognitive testing revealed significant differences
in the executive functioning of offspring of mothers who smoked
marijuana, compared with children of abstaining moms.

Researchers have a limited ability to measure executive functioning in
very young children, he explains. "If there were better tests, the
differences might have been spotted sooner."

In recent years, the Ottawa researchers started doing functional MRI
brain scans on the study participants. These hightech fMRI tests
reveal that offspring exposed to marijuana prenatally seem to "utilize
different parts of the brain" for performing certain tasks in
comparison to unexposed offspring.

"It's almost like the brain corrected itself" for the changes brought
about by marijuana exposure, Fried says. "But interestingly, the
length of time it took the subjects to respond [to a task] was
somewhat longer."

One thing is clear from the research: "The more the woman smokes up,
the greater the likelihood there will be some effect on the
offspring," Fried says.

He emphasizes that his study was launched in the late 1970s, when
marijuana was far less potent than it is today. The concentration of
tetrahydrocannabinol (THC) - the ingredient that makes people feel
high - is much greater now. So, it's possible that studies based on
exposure decades ago "may represent a somewhat conservative picture of
the impact of marijuana use on a developing fetus," Fried says.

The effects may also vary depending on how the marijuana is consumed -
whether it is smoked or consumed as an oil or edible. Smoke from a
marijuana cigarette contains five times more carbon monoxide than the
smoke from a tobacco cigarette, which can affect the amount of oxygen
reaching the fetus.

Many public-health experts are concerned more pregnant women will use
marijuana once Canada legalizes recreational pot next year.

There are no reliable statistics on how many Canadians currently smoke
marijuana during pregnancy. U.S. studies have found that 4 per cent to
6 per cent of pregnant women acknowledge using it, although that
figure is likely an underestimate, Lurie says.

The move to legalization seems to be reducing the stigma associated
with marijuana consumption. "People just don't even consider it to be
a drug," Lurie says. Some health-care providers have noticed that more
and more women are willing to discuss their use of cannabis during
pregnancy.

"They are letting their guard down and feel safer disclosing its use,"
says Kelly Polci, a social worker in the Women and Babies Program at
Sunnybrook Health Sciences Centre in Toronto.

In some cases, women struggling with morning sickness are turning to
marijuana - a remedy that is promoted on some websites.

"There is a lot of messaging on the Internet saying that marijuana is
safe to use during pregnancy, while it is actually not," says Dr. Maya
Nader, a family physician at St. Michael's Hospital in Toronto.

"Women need to know that health-care providers can recommend other
morning-sickness treatments that don't carry the risks of marijuana."

What's more, women should also be aware that breastfeeding and
marijuana are a bad combination. THC is stored in fat tissue and can
remain there for up to two months, gradually being released into
breast milk. That means some children can get a dose of THC from
breastfeeding - even after their mothers have stopped smoking
marijuana, Nader says.

Abstinence is the best approach. But if a pregnant woman or new mom is
having trouble quitting, she should talk to her doctor in order to
reduce the potential harm to her offspring, Lurie advises.

----------------------------

Paul Taylor is a patient navigation advisor at Sunnybrook Health
Sciences Centre. He is a former health editor of The Globe and Mail.
You can find him on Twitter  and online at Sunnybrook's
Your Health Matters