More than two thirds (69%) of cannabis dispensaries in Colorado recommended cannabis products for relief of severe nausea during the first trimester of pregnancy, a new study has found.

That number jumped to 83% among medical dispensaries compared with those that just dispense recreational marijuana.

The findings were published online May 7 in Obstetrics & Gynecology by Betsy Dickson, MD, from the University of Colorado School of Medicine and Colorado School of Public Health, Aurora, and colleagues.

In the journal podcast, senior author Torri D. Metz, MD, from the Denver Health and Hospital Authority, Colorado, said she was surprised by the high number of dispensaries recommending marijuana, as Colorado has a robust public health education program that warns of the dangers of cannabis use during pregnancy and lactation through radio messages, billboards, and a website.

"There is no way that people working at these dispensaries haven't been exposed to that education...It was surprising to me that despite that push, despite these [product] warning labels that say these may be harmful to pregnant women...they're still advising use," she noted, stressing that their recommendation would be to avoid cannabis use altogether during pregnancy.

A Third of Dispensaries Say Cannabis Use Is "Safe" During Pregnancy

For the study, two of the researchers phoned 400 cannabis dispensaries in Colorado — a state that has legalized medical and recreational marijuana use — posing as a woman 8 weeks pregnant with severe nausea.

Reading from a script, the callers asked dispensary employees whether they would recommend anything for morning sickness, whether marijuana use is safe during pregnancy, whether the caller could use her medical marijuana card to buy marijuana, and whether she needed to talk with her healthcare provider.

The primary objective was to estimate the proportion of cannabis dispensaries whose staff recommended cannabis to a caller pretending to have first-trimester nausea.

Cannabis products were recommended by 83.1% of medical dispensaries, 60.4% of retail dispensaries, and 61.7% of dispensaries that were both medical and retail (P < .001). Results were similar when analyzed by population density (urban, 71% vs rural, 63%; P = .18).

Researchers were surprised that cannabis recommendations were more likely at medical than retail dispensaries. "We actually expected it would be the other way around," Metz said.

Some employees (9%) initially said they could not recommend any products, but then did give a recommendation, and this was similar among all dispensary types (medical, 8.8%; retail, 7.2%; both, 10.6; P = .65).

More than one third (35.7%) of dispensaries said cannabis use during pregnancy is safe, and results did not vary significantly by dispensary type (medical, 40.7%; retail, 28.4%; both, 34.5%; P = .24).

"That's pretty high when they are specifically endorsing safety and we certainly don't have any safety data," Metz observed in the podcast.

Just 4.7% of dispensaries said there was a risk of fetal harm and only 1.8% said there was a risk for harm to both the mother and fetus.

The proportion of dispensaries that said cannabis use can be harmful did not differ when analyzed by dispensary type or population density.

Women Not Getting Sound Advice

Of those that recommended a product, 65% of dispensaries based their recommendation for prenatal use on personal opinion and 30% did not give a reason.

Dispensary employees who made their recommendations based on personal opinion did so much more frequently at medical dispensaries (85%) compared with retail (57%) and both (45%) (P < .001).

Although 81% of dispensaries recommended women speak with their healthcare provider, that advice only came after employees were prompted near the end of the call.

Just 32% of dispensary employees made the recommendation independently.

Metz said after legalization she initially saw an uptick in the number of pregnant women who told her they use marijuana, which has now declined.

"I think that's tapered off because marijuana has remained a Schedule I drug. There are still implications in Colorado for reporting to social services," she noted.

"Pregnant women who are interested in using marijuana may refrain from seeking safety information from healthcare providers as a result of fear of legal repercussions and instead seek advice from cannabis retailers," the researchers write.

No Data to Support Safety of Pot During Pregnancy, Evidence of Harm

There are no data to support the use of marijuana for morning sickness, and studies have yielded conflicting results regarding the safety of cannabis use during the first trimester of pregnancy.

But Metz said there are more data on cannabis use during pregnancy not isolated by trimester that demonstrate the potentially harmful effects on fetal growth and neurologic development, and studies show an increased risk for neonatal intensive care unit admission when cannabis has been used during pregnancy.

"There's definitely concern in the available literature that there is a potential for harm, and that is definitely not being communicated to pregnant women by dispensaries in Colorado," Metz stressed.

"[We] need to send patients a clear message, and it's OK to do that with the caveat that 'we haven't answered all the questions, we're still working on that…but we're worried about harm and we really would recommend you not use it during pregnancy,' " she explained.

The researchers say their sample size was calculated for the study's primary outcome and may not have been large enough for some secondary outcomes.

Laura M. Borgelt, PharmD, reports receiving a grant from the Colorado Department of Public Health and Environment for a study on cannabidiol for refractory pediatric epilepsy. She has served on working groups for the Colorado Department of Revenue and CDPHE regarding use of cannabis and patient safety. The other authors have reported no relevant financial relationships.

Obstetrics & Gynecology. Published online May 7, 2018. Full text

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