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 “In co-users of both marijuana and cigarettes we noted an increase
in smaller babies, earlier deliveries, asthma, and pregnancy-related
hypertension,” Dr. Diana Racusin, an author of the study, told
Reuters Health by email.
As marijuana becomes legal in more places, more women are using the
drug while pregnant, partly because they view it as less risky than
other substances, said Racusin, a maternal-fetal medicine fellow at
Baylor College of Medicine in Houston, Texas.
Smoking cigarettes during pregnancy is already linked to problems
for babies, including low birth weight and early delivery.
Little is known about the effects of marijuana during pregnancy,
even though it’s estimated that between 2 percent and 11 percent of
U.S. pregnant women use the drug, the authors write in the American
Journal of Obstetrics and Gynecology.
To see what effects marijuana alone or in combination with
cigarettes might have on both mothers and babies, the study team
analyzed data on 12,069 women who gave birth between January 2011
and June 2015 at hospitals associated with Baylor College of
Medicine.
The participants were all surveyed around the time of delivery about
their use of marijuana, tobacco and other nicotine-containing
products during pregnancy. The researchers gathered information
about birth outcomes from medical records.
Of the entire group, 106 women, or less than 1 percent, reported
using marijuana while pregnant. And 48 of these, or just under half
the marijuana users, said they also smoked cigarettes while
pregnant.
Overall, a total of 242 women, or 2 percent of the study
participants, reported having smoked cigarettes.
Researchers found that women who smoked both marijuana and tobacco
were more than twice as likely as women who used neither substance
to experience asthma, two and a half times as likely to deliver
prematurely and nearly three times as likely to have babies with
small heads or low birth weight.
Smoking cigarettes alone was also linked to smaller infant head
size, lower birth weight and premature delivery, but these risks
were higher when combined with marijuana use.
There were no significant differences, meaning differences larger
than could be due to chance, between women who smoked just
marijuana, or their babies, and women who did not smoke anything and
their babies.
Women who smoked either pot or cigarettes but not both did not have
significantly higher rates of pregnancy-related high blood pressure
than nonsmokers. But women who smoked both substances were two and a
half times more likely to have pregnancy-related high blood
pressure.
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The study team notes that women who reported using both marijuana
and tobacco were more likely than the others to have diabetes and
high blood pressure before pregnancy.
Women who used only tobacco during pregnancy or only marijuana, and
those who used both, were also four to seven times more likely than
women who used neither to have depression or anxiety.
Mothers who did not get sufficient prenatal care, meaning they went
to fewer than 11 doctor visits during pregnancy, were more likely to
smoke either marijuana or cigarettes.
Dr. Carri R. Warshak, an associate professor at the University of
Cincinnati in Ohio who studies the effects of marijuana use in
pregnancy, said that the most consistent effect is a lower birth
weight in babies.
“When babies are born both small and premature, the birth weight
becomes vitally important for improving survival and healthy
outcomes,” said Warshak, who was not involved in the study.
Babies who are born small are at greater risk for feeding
difficulties and jaundice and may even experience heart problems
later in life, she added.
“We are only now beginning to learn about the ramifications of
marijuana use in pregnancy,” Racusin said.
“Tobacco use is clearly detrimental to fetal health, and therefore
baby health. It is very likely that marijuana use shares some of the
untoward effects. To optimize fetal health and the health of the
child, it is best to avoid use of marijuana and tobacco in
pregnancy,” Warshak said.
SOURCE: bit.ly/28l6WLp American Journal of Obstetrics and
Gynecology, online June 2, 2016.
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