New research shows the use of cannabis among pregnant women is increasing as both medical and recreational marijuana are legalized in more states. 

According to a 2019 study in the Journal of the American Medical Association, past-month cannabis use by pregnant women nearly doubled between 2002 and 2017, and daily or near daily cannabis use in pregnant women has more than tripled during that period, despite a lack of in-depth research into long-term side effects.

Knowing those statistics, addictions researcher Celestina Barbosa-Leiker, who currently serves as the vice chancellor for research at Washington State University Health Sciences Spokane, is conducting her own research studies to determine why that trend has developed.

“Our state’s perception of cannabis use has changed a lot since legalization, and overall, we’re seeing cannabis use by pregnant women increasing both locally and nationally,” she says. “Therefore, we wanted the patient perspective on cannabis use during pregnancy and postpartum as to why pregnant women are using cannabis and how we can better help them and their babies with their overall health.”

Prior to Washington state’s legalization of recreational marijuana, Barbosa-Leiker had been studying opioid and alcohol use, which she says led directly into her interest in starting research of cannabis use by pregnant women.

“Through my background studying women with opioid disorders, I understood that there were women who were considering cannabis as an alternative for pain management,” she says. “After legalization, I began hearing more about increased use by pregnant women and I wanted to research the reasons behind that.”

Barbosa-Leiker says cannabis use during pregnancy has been linked to low birth weights and a moderate risk of still birth.

“There have been some longitudinal studies following kids born to mothers who had used cannabis that showed some impaired cognitive function as the children grew,” she says. “However, those studies were conducted 20 to 30 years ago, when the potency of cannabis products was significantly less, and there were fewer varieties of products available.”Barbosa-Leiker says those risks likely have increased with stronger cannabis products that can be consumed in a variety of ways.

“I think it’s possible we’re underestimating the current risk, simply because the long-term use of these products hasn’t been studied,” she says.

In her research involving cannabis use during pregnancy, Barbosa-Leiker has conducted three studies.

The first study included a series of interviews with women who disclosed daily use of cannabis during pregnancy, while the second and third studies focused on interviews with health care providers and cannabis retailers.

“We originally had just pregnant women and health care providers as participants,” she says. “However, we learned in the study with pregnant women that many of them sought information from cannabis retailers, so that is why we added a retailers study.”

Barbosa-Leiker says the first study included interviews with 19 women who were pregnant or had given birth recently and who used cannabis daily while pregnant.

“We started recruiting volunteer subjects for the first study in January 2018, completed the study in 2019, then analyzed the data,” she says. 

That study is expected to be available online, through The Journal of Addiction Medicine, in early February. The remaining two studies should be published later that month.

She says the studies were funded by the WSU alcohol and drug abuse research program and cost an estimated $25,000. Included in that grant funding, she says, is a fourth, longitudinal study for which WSU researchers are still recruiting participants and collecting data. The fourth study asks pregnant women to fill out surveys regarding stress and other variables, and then invites them back two months postpartum for a video session of natural play with their infant.

Overall, Barbosa-Leiker says the main purpose of all four studies is to improve patient and provider education on the topic of cannabis use during and after pregnancy.

“Many of these women have traumatic backgrounds or health conditions that need to be taken into account, so it’s not enough to simply ask if they’re using cannabis. We need to be asking why and what can be done to help,” she says. “Going forward we also need to work on better health messaging that will enable people to make informed decisions without fear of being stigmatized.” 

Barbosa-Leiker says researchers recruited study participants through Craigslist and with fliers placed in offices of local obstetricians.

Although researchers were simply interviewing their subjects and weren’t providing cannabis or encouraging participants to use it, Barbosa-Leiker says the study was subjected to an added level of review.

“Because this study involved a substance that is legal on the state level but illegal federally, we did have additional reviews and took precautions to ensure participants’ safety.”

She says the majority of the first study participants were pregnant at the time of interview, and most weren’t first-time mothers.

“A lot of them reported having used cannabis during previous pregnancies or postpartum while breastfeeding,” she says. “Those we spoke with felt the children from those pregnancies were healthy and didn’t appear to be negatively affected by their use of cannabis during or just after pregnancy.”

Barbosa-Leiker says researchers learned several things from talking with pregnant women in the initial study.

“The first thing we found was that many participants were initially using cannabis to help manage other conditions, including chronic pain, fibromyalgia, depression, and anxiety,” she says. “However, after they found out they were pregnant, their main concern was figuring out whether they could still safely use cannabis to manage those conditions while not harming their babies.”

She says participants also expressed frustration with the lack of research available on cannabis use while pregnant and talked about getting mixed messages from providers as to the risks of continuing to use.

“A lot of the participants had looked online for research and information on how to decrease their use or whether certain products or methods of consumption might be healthier or contain fewer chemicals,” she says. “Some talked about hearing inconsistent messages from health care providers they’d asked, and many were also strongly concerned about legal consequences of continuing use because of federal laws.”

She says most study participants simply wanted to learn more in order to be able to make the best decision for themselves and any future children.

“As a researcher, I knew we were lacking in this area, and it was obvious these women are also feeling that,” she says. “We’re really one of the first to do a study that interviewed patients in a state where cannabis has been legalized.”

Barbosa-Leiker says participants were quite willing to share their stories, saying most of the stigmatization they felt was in disclosing cannabis use at prenatal visits to health care providers.

“From a health policy perspective, it’s difficult because like alcohol or tobacco, cannabis is now legal but not necessarily safe,” she says. “It will likely take decades to get to the level of research we need to be able to determine all the aftereffects.”