Cannabis use among pregnant women in California nearly doubled between 2009 and 2017, according to new data released today.
Marijuana has been legal for medical purposes in the state since 1996, and recreationally since 2016.
Researchers tracked 370,000 pregnancies in Northern California for nine years and found that, as of 2017, 3.4 percent of expectant mothers used the drug, up from 1.9 percent in 2009.
The rate of women using the drug in the year before pregnancy also rose by almost double, from 6.8 percent to 12.5 percent.
And those who do use marijuana are using it more often: 21 percent of women who use cannabis during pregnancy use it daily (up from 15 percent in 2009), and 27 percent use it weekly (up from 25 percent).
Experts reacting to the report, by Kaiser Permanente, said it is cause for concern: while we still do not fully understand the effects of marijuana on fetal brains, there is evidence of damaging side effects. And yet, rates of seem to be rising faster than science can keep up.
The rate of women using the drug in the year before pregnancy also rose by almost double, from 6.8 percent to 12.5 percent, with a sharp uptick after 2016, when cannabis was legalized for recreational use
This graph shows the rate of women who reported using cannabis during pregnancy, collated by frequency of use. Those who do use marijuana are using it more often, they found. Looking within these lines, 21 percent of women who use cannabis during pregnancy use it daily (up from 15 percent in 2009), and 27 percent use it weekly (up from 25 percent)
‘Research evaluating the potential adverse health effects of marijuana on pregnancy outcomes has not kept up with rapidly expanding legalization and access to cannabis products across the United States,’ OBGYNs Dr Torri D. Metz and Dr Elaine H. Stickrath, of University of Utah Health, write in an editorial published with the study in JAMA Network Open on Friday.
‘As clinicians, we must remind reproductive-aged women that there are no known benefits of marijuana use in pregnancy and that there are associated harms.’
There are some caveats to the data: it was self-reported, and pregnant women were identified as marijuana users in their first prenatal visit to Kaiser Permanente in Northern California, often at roughly eight weeks gestation, when they may not yet know they are pregnant.
However, it correlates with most other research on trends in pregnancy and cannabis.
In December 2017, the same team, led by Kelly Young-Wolff, PhD, a research scientist, found a rise in the rate of urine samples of pregnant women that tested positive for cannabis at their hospital in Northern California.
In 2018, they found pregnant women being treated at Kaiser with severe morning sickness were nearly four times more likely to use the drug in their first trimester.
And studies elsewhere suggest this paper is not isolated.
Most women in the US, where cannabis is increasingly legal, believe marijuana does little to no harm to a pregnancy. And most dispensaries in Colorado, one of the first places to legalize recreational marijuana in the US, sell the drug for morning sickness.
There is very little research on the topic to give expectant mothers guidance.
There is some evidence that the drug could be harmful, but it is not weighty enough to draw a strong conclusion.
As such, research projects are popping up all over the country to fast-track some answers.
In Colorado, researchers funded by the Centers for Disease Control and Prevention (CDC) are studying marijuana’s impact on breast milk. Another in Colorado, funded by the National Institute on Drug Abuse (NIDA), is looking at fetal brains. One at the University of North Carolina is also looking at fetal brains.
The latest to launch, in May, is at the University of Washington School of Medicine: ‘Moms + Marijuana’, a project seeking 70 pregnant women who use cannabis to examine the effects of the drug on infants’ brains.
In a bid to rally participants, they are offering $300 to women aged 21 to 34 years old, who are less than 13 weeks pregnant, to be monitored through their pregnancy. Signing up, the women agree that their newborn will undergo MRI brain scans at six months old to be compared with brains of babies whose moms did not use cannabis, alcohol or cigarettes.
Each of the studies have sparked ire from people who are staunchly anti-cannabis, including the customary reaction from journalist Alex Berenson, who compared the Washington study to Tuskegee, when African American men with syphilis were duped by scientists, who gave them a placebo, knowing it would harm them.
Most in the medical community agree that, despite the risks of low birth-weight and impaired brain development, it’s important to conduct a study to work out what those risks are, since many cannabis dispensaries already promote their products to treat morning sickness.
But given that they are all still in their early stages, the American College of Obstetricians and Gynecologists (ACOG) does not recommend using the drug in pregnancy, to err on the side of caution.
That may be increasingly difficult, Dr Young-Wolff warns in today’s study.
Cannabis is so rigorously marketed online, particularly as a wellness product, with little oversight.
‘There is still much that is unknown on the topic, including what type of cannabis products pregnant women are using and whether the health consequences differ based on mode of cannabis administration and frequency of prenatal cannabis use,’ Dr Young-Wolff said.
Senior author Dr Nancy Goler, an OBGYN at Kaiser, added: ‘There is an urgent need to better understand the effects of prenatal cannabis exposure as cannabis becomes legalized in more states and more widely accepted and used.
‘Until such time as we fully understand the specific health risks cannabis poses for pregnant women and their fetuses, we are recommending stopping all cannabis use prior to conceiving and certainly once a woman knows she is pregnant.’