During her pregnancy, she never drank
alcohol or had a cigarette. But nearly every day, Stacey, then 24, smoked
marijuana.
With her fiancé’s
blessing, she began taking a few puffs in her first trimester to quell morning sickness before
going to work at a sandwich shop. When sciatica made it
unbearable to stand during her 12-hour shifts, she discreetly vaped marijuana
oil on her lunch break.
“I wouldn’t necessarily
say, ‘Go smoke a pound of pot when you’re pregnant,’” said Stacey, now a
stay-at-home mother in Deltona, Fla., who asked that her full name be withheld
because street-bought marijuana is illegal in Florida. “In moderation, it’s
O.K.”
Many pregnant women,
particularly younger ones, seem to agree, a recent federal survey shows. As
states legalize marijuana or its medical use, expectant mothers are taking it
up in increasing numbers — another example of the many ways in which acceptance
of marijuana has outstripped scientific understanding of its effects on human
health.
Often pregnant women
presume that cannabis has no consequences for developing infants. But
preliminary research suggests otherwise: Marijuana’s main psychoactive
ingredient — tetrahydrocannabinol, or THC — can cross the placenta to reach the
fetus, experts say, potentially harming brain development, cognition and birth
weight. THC can also be present in breast milk.
“There is an increased
perception of the safety of cannabis use, even in pregnancy, without data to
say it’s actually safe,” said Dr. Torri Metz, an obstetrician at Denver Health
Medical Center who specializes in high-risk pregnancies. Ten percent of her
patients acknowledge recent marijuana use.
In the federal survey, published online in
December, almost 4 percent of mothers-to-be said they had used marijuana in the
past month in 2014, compared with 2.4 percent in 2002. (By comparison, roughly
9 percent of pregnant women ages 18 to 44 acknowledge using alcohol in the
previous month.)
Young mothers-to-be
were particularly likely to turn to marijuana: Roughly 7.5 percent of 18- to
25-year-olds said they had used pot in the past month in 2014, compared with 2
percent of women ages 26 to 44.
Evidence on the effects
of prenatal marijuana use is still limited and sometimes contradictory. Some of
the most extensive data come from two sets of researchers, in Pittsburgh and in
Ottawa, who have long studied children exposed to THC in the womb.
In Pittsburgh,
6-year-olds born to mothers who had smoked one joint or more daily in the first
trimester showed a decreased ability to understand concepts in listening and
reading. At age 10, children exposed
to THC in utero were more impulsive than other children and less able to focus
their attention.
Most troubling,
children of mothers who used marijuana heavily in the first trimester had lower
scores in reading, math and spelling at age 14 than their peers.
“Prenatal exposure can
affect the adolescent pretty significantly,” said Dr. Lauren M. Jansson, the
director of pediatrics at the Center for Addiction and Pregnancy at the Johns
Hopkins University School of Medicine.
Several studies have
found changes in the brains of fetuses, 18 to 22 weeks old, linked to maternal
marijuana use. In male fetuses who were exposed, for instance, researchers have
noted abnormal function of the amygdala, the part of the brain that regulates
emotion.
“Even early in
development, marijuana is changing critical circuits and neurotransmitting
receptors,” said Dr. Yasmin Hurd, a neuroscientist and the director of the
addiction center at Icahn School of Medicine at Mount Sinai in Manhattan.
“Those are important for regulation of emotions and reward, even motor function
and cognition.”
It is already well
documented that the developing brains of teenagers can be altered with regular
marijuana use, even eventually reducing I.Q.
“The effects are not
dramatic, but that doesn’t mean they are not important,” said Jodi Gilman, an
assistant professor of psychiatry at Harvard Medical School who studies
adolescent users of cannabis. “It could make the difference between getting an
A and getting a B.”
“You could imagine that
a similar subtle effect may be present in those who were exposed prenatally to
marijuana,” she added.
The American Academy of Pediatrics and the American
College of Obstetricians and Gynecologists both advise against
prenatal cannabis use because of its links to cognitive impairment and academic
underachievement. But many state and federal agencies avoid the topic.
Of five federal
agencies, only the National Institute on Drug Abuse had any information about
prenatal marijuana use on its website as of last February, according to a study published online in December in
the journal Substance Abuse. Only 10 state health departments did.
Until recently, the Centers
for Disease Control and Prevention offered nothing.
“I don’t think public
health officials should be alarming people,” said Marian Jarlenski, the study’s
lead author and an assistant professor at the University of Pittsburgh Graduate
School of Public Health. “They just have to say, ‘There have been studies done,
and there is some risk.’”
In a statement, C.D.C.
officials expressed concern about memory and attention problems among children
exposed to THC in utero.
“While current evidence
on health consequences is inconsistent, some studies have found risks
associated with marijuana use during pregnancy, such as low birth weight or
preterm birth,” the agency said.
Comments