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 Among teen mothers under age 18, marijuana use during pregnancy
surged from about 13 percent in 2009 to almost 22 percent in 2016,
researchers found. Over that same period, the proportion of pregnant
women aged 18 to 24 using marijuana rose from 10 percent to 19
percent.
Across all age groups, marijuana use during pregnancy increased from
4 percent at the start of the study to 7 percent by the end.
“Prior nationally representative studies have found that the
prevalence of marijuana use among U.S. adult pregnant women has
increased over time; however, these studies have not included
objective measures of biochemically verified marijuana use and
likely underestimate the prevalence,” said lead study author Kelly
Young-Wolff and senior author Dr. Nancy Goler, both of Kaiser
Permanente Northern California in Oakland.
“Our study is important because it addressed key limitations of
prior studies by investigating trends in prenatal marijuana use
using data from a large California healthcare system with ‘gold
standard’ universal screening for prenatal marijuana use,” the
authors said in an email.
Marijuana is the most commonly used illegal drug during pregnancy,
researchers note in JAMA. Some previous research suggests that
prenatal marijuana exposure may impair fetal growth and
neurodevelopment.
For the study, researchers examined data on more than 279,000
pregnant women who were treated at Kaiser Permanente facilities that
did universal screening for marijuana use as part of standard
prenatal care.
Women typically completed questionnaires asking about drug use when
they were around eight weeks pregnant and then got lab tests during
the same checkup or within the next two to four weeks.
Drug tests sometimes revealed marijuana use that patients didn’t
disclose on the questionnaires, and some women who reported drug use
passed the screening tests, the study found.
Among women who screened positive for marijuana use, 55 percent
failed the lab tests but denied drug use on the questionnaires.
Another 16 percent of women passed the drug tests but disclosed
marijuana use on the questionnaires.
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It’s possible, but unlikely, that some lab tests revealed drug use
before pregnancy because marijuana can be detected up to about 30
days after the last use, researchers note. The results of drug
screening early in pregnancy also might not reflect what happens for
the remainder of pregnancy.
“We are just scratching the surface in terms of understanding
cannabis use in pregnancy,” said Dr. Marcel Bonn-Miller, a
researcher at the University of Pennsylvania Perelman School of
Medicine in Philadelphia who wasn’t involved in the study.
Although results from screening in Northern California might not
reflect rates of drug use in other parts of the study, the trend is
still alarming, Bonn-Miller said by email.
“The more we study cannabis use during pregnancy, the more we are
realizing how harmful it can be,” Bonn-Miller added.
Marijuana use in pregnancy may be on the rise in part because the
legalization of medical marijuana has made people think of the drug
as less dangerous, even during pregnancy, said Barbara Yankey, a
public health researcher at Georgia State University in Atlanta who
wasn’t involved in the study.
“Because of the possibility of concurrent use of marijuana and other
substances of abuse, the evidence of its direct association with
preterm labor, fetal growth restriction, preterm birth, low
birthweight and stillbirth is still debatable, though these adverse
effects lean more towards an increased likelihood of occurrence,”
Yankey said by email.
“Developmental adverse effects and complications of marijuana use on
the unborn child also depend on the frequency and dose of marijuana
use,” Yankey added.
SOURCE: http://bit.ly/2BDaMEa JAMA, online December 26, 2017.
(This story corrects lead author's name in paragraph 4 (Young-Wolff)
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