Pot Use In Pregnancy Is Going Up. Here's What We Know So Far About Its Effects

It could have some serious, long-term effects on the child.
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Pregnant women are using more pot than they used to, according to a large survey of 200,000 women in the U.S.

While rates of use are still low overall among pregnant women, they’ve increased a dramatic 62 percent over the past 12 years, rising from 2.4 percent in 2002 to 3.9 percent in 2014, with young women primarily driving the increase. While only about 2.1 percent of women ages 26 to 44 used marijuana while pregnant, 7.5 percent of women 18 to 25 have done the same.

Experts aren’t sure why pot use has increased among pregnant women, and especially younger pregnant women. One leading theory is that the growing acceptance of medical marijuana as a treatment for nausea may have encouraged women to use cannabis to help them cope with morning sickness. This may especially be the case for women who have an extreme version of pregnancy nausea called hyperemesis gravidarum, according to an accompanying editorial written by scientists at the National Institute on Drug Abuse.

Studies are still emerging about cannabis’ potential effect on a developing fetus, but early research suggests there may be some immediate and long-lasting consequences for a newborn’s birth weight and a child’s memory and verbal reasoning skills.

What we know about pot and pregnancy

The truth is that scientists don’t know a lot of about how cannabis affects a growing fetus, because it’s difficult to isolate pot use from other factors in a pregnant woman’s life. People who use pot in general are more likely to smoke, drink alcohol and use other drugs, and women who use drugs during pregnancy are also less likely to get adequate nutrition and prenatal care.

But the most comprehensive research thus far, a 2016 meta-analysis of 24 previous studies, concluded that newborns exposed to cannabis in the womb were more likely to weigh less at birth compared to babies without exposure. Lower birth weight is linked to an increased risk of certain infections early in life and chronic health conditions in adulthood. The study also found these babies had double the odds of spending time in the neonatal intensive care unit compared to babies without pot exposure, which means they were likely born prematurely. However, many of the studies included in the analysis could not isolate the effects of cannabis from other factors like tobacco and alcohol use.

A 2011 review of two long-term studies looked at the effects beyond infancy, and concluded kids exposed to pot in utero had an increased risk of cognitive deficits like short-term memory problems and lower verbal reasoning skills, suggesting that marijuana may have long-term consequences on a child’s brain. Among the 3- to 4-year-olds studied, overall intelligence scores did not fluctuate, but there were deficits in memory and verbal skills for those children who’d been exposed.

Other problems, including decreased attention skills, impulsiveness, hyperactivity and depression, began to emerge at ages five and six and persisted in varying amounts through the ages of nine through 12. However, the researchers admit it was difficult to find a clear pattern between in utero cannabis exposure, the amount of cannabis mothers used, and its effects on children’s health.

The complicating factor of medical marijuana

Currently, 29 states and Washington, D.C. allow marijuana for medical purposes, and the number of legal pot users will continue to grow if more states follow suit. There isn’t much data on whether doctors are prescribing marijuana for pregnancy nausea, but a 2014 study on pregnant women in Hawaii found that those with severe nausea were more likely to say they used marijuana during pregnancy compared to those who didn’t have intense symptoms. There are websites describing the use of marijuana for pregnancy nausea, NIDA researchers noted in their editorial, and almost 70 percent of pregnant women in the U.S. experience some level of nausea during their pregnancies.

NIDA researchers conclude their editorial by recommending that pregnant women avoid cannabis, and suggest that OB/GYNs and doctors who prescribe marijuana follow guidelines set forth by the American College of Obstetrics and Gynecology, which discourages marijuana use among pregnant women, breastfeeding women, and women who are trying to get pregnant.

They also recommended more and better research that can isolate the effects of cannabis, particularly high-potency pot products and synthetic cannabinoids. However, given ethical concerns, these studies could never take the form of a randomized controlled trial. Though such trials are the gold standard of scientific evidence, it would be unethical to ask pregnant women to use pot in a study because scientists aren’t sure what effect it will have on their fetuses.

The results were published Monday in the medical journal JAMA.

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Before You Go

1969: Little Support For Legalizing Marijuana

50 Years Of Marijuana Polling


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