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Marijuana use among pregnant teens has spiked in California

Most experts agree smoking weed while pregnant is probably a bad idea

California already has the world’s largest pot economy and the state is preparing to legalize recreational sales on Jan. 1. But a new study about marijuana use by pregnant women suggests the pot boom is having an overlooked impact on public health.

Researchers from Kaiser Permanente Northern California in Oakland looked at data collected from 279,000 pregnant women who completed a screening for marijuana use as part of standard prenatal care. Across all age groups in the study, marijuana use by pregnant women saw a modest increase from 4 percent in 2009 to 7 percent in 2016. But over that same period, self-reported weed use by expectant teens under 18 soared from 13 percent to nearly 22 percent, and from 10 percent to 19 percent among pregnant women ages 18 to 24. The researchers noted previous studies found that from 2002 to 2014, the prevalence of self-reported, past-month marijuana use among adult pregnant women across the U.S. increased from 2.4 percent to 3.9 percent, while 14.6 percent of pregnant adolescents reported past-month pot use. But they also pointed out that past research relied on self-reported surveys, which likely underestimate the scope of the problem since most women will be reluctant to admit getting high while pregnant.


“We are just scratching the surface in terms of understanding cannabis use in pregnancy,” Dr. Marcel Bonn-Miller, a researcher at the University of Pennsylvania Perelman School of Medicine in Philadelphia, who wasn’t involved in the study, told Reuters. “The more we study cannabis use during pregnancy, the more we are realizing how harmful it can be.”

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The California Department of Public Health has already started to warn pregnant women about the dangers of getting stoned. The department maintains a webpage called “Let’s Talk Cannabis,” which includes a section that says “if you use cannabis while you are pregnant or breastfeeding the growth and development of your baby’s brain can be harmed, and your baby is more likely to be born with a lower birth weight and to have health problems.” Ellen Komp, deputy director of California’s chapter of National Organization for the Reform of Marijuana Laws, told the Los Angeles Times that the site is “fairly accurate,” but added that it goes too far in some aspects. “The risks with pregnancy are somewhat overstated, telling women they should not use cannabis for nausea or even if they are thinking of getting pregnant,” Komp said.

The American College of Obstetricians and Gynecologists discourages marijuana use by women who are pregnant or breastfeeding. Pregnant women who get high tend to use multiple substances, so the exact nature of the link between low birthweight, stillbirth, and other complications is still unclear. But most experts agree that smoking weed while pregnant is probably a bad idea.


“The science is incomplete, but the public health message is clear: To have the healthiest baby possible, avoid using marijuana, alcohol, and tobacco during your pregnancy,” wrote Therese Grant, director of the fetal alcohol and drug unit at the University of Washington Medical Center.

Outside of California, there’s anecdotal evidence that marijuana use by pregnant women is already an issue in states that have legalized. Colorado health care providers are supposed to ask about marijuana use during prenatal visits. One hospital in Pueblo, Colorado, reported that nearly half the babies tested at the facility in one month in 2016 had marijuana in their system. The hospital supported an initiative to ban recreational marijuana sales in the city.

Women in California, Colorado, and other states who use marijuana during pregnancy also risk an intervention from Child Protective Services, which could lead to loss of custody or, in some places, criminal prosecution. The laws typically don’t make exceptions for medical use or instances where the mother is substituting marijuana for opioids or other substances that are known to be more harmful. And while smoking weed while pregnant can lead to legal problems, there’s no punishment for smoking cigarettes or other harmful behaviors.

The American Medical Association and many other organizations have warned that policies that punish women for using drugs while pregnant tend to backfire by pushing them away from prenatal care. As states have learned during the opioid crisis, the best way to help expectant mothers with drug problems is to make sure they get help and support — not lock them up and take away their babies.