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As more states legalize marijuana, more women are using cannabis during pregnancy. Getty Images
  • More women are using cannabis while they’re pregnant according to a new study.
  • The study found that women using cannabis while pregnant increased from nearly 2 percent to 3.4 percent.
  • Experts say early research shows that cannabis use during pregnancy may cause neurological effects as well as potentially raise the risk of autism.

As laws and attitudes around cannabis have shifted, a growing number of people, including pregnant women, are reportedly using cannabis on an occasional or regular basis.

Thirty-three states and the District of Columbia have legalized medical cannabis use. Additionally, 11 states and the District of Columbia have legalized recreational cannabis (marijuana) use.

According to a study published last year by researchers in California, more women are reportedly using cannabis while they’re pregnant.

The rise of cannabis use among pregnant women has worried certain health experts who say the drug may affect the development of the fetus, including potentially increasing the risk of autism.

The authors of this study assessed cannabis use among pregnant women in the Kaiser Permanente Northern California healthcare system.

In this healthcare system, pregnant women are asked to complete a questionnaire about drug use during their first prenatal care visit.

The researchers found that from 2009 to 2017, the self-reported rate of cannabis use during pregnancy increased from 1.95 percent to 3.38 percent.

Over the same time period, the self-reported rate of cannabis use during the year before pregnancy increased from 6.80 percent to 12.50 percent.

Among pregnant women who were surveyed in 2017, 0.69 percent of them reported using cannabis on a daily basis while pregnant. In comparison, 0.92 percent reported using cannabis on a weekly basis while pregnant, and 1.77 percent reported using it on a monthly basis or less.

More frequent cannabis use was associated with younger age, African American ethnicity, and lower-median neighborhood household income.

Other research has found that some women use cannabis as an alternative to other treatments to manage pregnancy-related symptoms like morning sickness or other health conditions.

“We use [cannabis] in chemotherapy patients when they have nausea, so patients think that it’s a good solution for morning sickness,” Dr. Jennifer Leighdon Wu, an obstetrician-gynecologist at Lenox Hill Hospital in New York, told Healthline.

“But when you think about morning sickness, it happens typically in the first trimester, when the brain and other organs are developing, so that’s the time when you really don’t want to be using [cannabis],” she said.

Instead, Wu suggests managing morning sickness with other medications for which more data is available on the safety during pregnancy.

Increasingly studies suggest that cannabis use during pregnancy may pose health risks to pregnant women and developing fetuses.

A review article published in 2016 found that women who used cannabis at least once a week while pregnant were more likely to deliver prematurely and more likely to have babies with low birth weights.

However, the authors of that review article noted that women who use cannabis more frequently also tend to use more tobacco and other drugs, which might help account for their findings.

Some research has also linked cannabis use in pregnancy to long-term neurological effects in children.

For example, children of mothers who used cannabis while pregnant may be at increased risk of poor academic performance and behavioral challenges.

A study published in August 2020 reported that women who used cannabis during pregnancy were 1.5 times more likely to have a child with autism.

The study reviewed every birth in the Ontario region of Canada between 2007 and 2012 before Canada approved recreational cannabis use in 2017.

For its findings, it focused on 2,200 women who said they used only cannabis during pregnancy without mixing it with alcohol, tobacco, or opioids.

More research is needed to study the short- and long-term effects of cannabis use in pregnancy, including occasional and frequent cannabis use, according to experts.

Given the potential safety risks and unanswered questions about cannabis use in pregnancy, the American College of Obstetricians and Gynecologists (ACOG) encourages women to avoid using cannabis while pregnant.

“Because of concerns regarding impaired neurodevelopment, as well as maternal and fetal exposure to the adverse effects of smoking, women who are pregnant or contemplating pregnancy should be encouraged to discontinue marijuana use,” writes the ACOG Committee on Obstetrics Practice in a committee opinion updated in 2017.

“Pregnant women or women contemplating pregnancy should be encouraged to discontinue use of marijuana for medicinal purposes in favor of an alternative therapy for which there are better pregnancy-specific safety data,” the committee adds.

Past research has found that when pregnant women report using cannabis, their doctors don’t always tell them about the potential health risks.

Even in states where cannabis use is legal, women may face penalties for using cannabis while pregnant under child protection policies.

And some women are also reluctant to report cannabis use due to legal concerns. Experts say punitive laws for pregnant woman using drugs may actually do more harm in the long run.

Although more research is needed on cannabis in particular, punitive policies that target drug or alcohol use in pregnancy may lead women to avoid prenatal care or treatment for substance use. The legal risks of using cannabis during pregnancy vary from one state to another.

“There are three main types of punitive policies related to drug use during pregnancy at the state level,” Sue Thomas, PhD, a senior research scientist at the Pacific Institute for Research and Evaluation (PIRE) in California, told Healthline.

“Women may be reported to Child Protective Services, women may be involuntarily committed in either jail or treatment settings, and women may face allegations of child abuse or neglect and possible termination of parental rights,” she said.

Women of color or low-income women are more likely than others to be targeted under such punitive policies, Thomas added. To learn about their legal rights, Thomas encourages women to contact a legal aid program.

“We have completed extensive research about policies related to both drug use during pregnancy and alcohol use during pregnancy,” Thomas said.

“This body of research indicates that most state policies related to drug or alcohol use during pregnancy, at best, have no health benefit and, at worst, lead to increases in low birth weight and preterm birth, and decreases in prenatal care use,” she said.