Leap in cannabis use by pregnant women prompts renewed health warnings

There are growing concerns that women in the US are turning to cannabis in an effort to alleviate pregnancy symptoms posing risks to both themselves, and their unborn children.

It has led to a call for pregnant women living in US states where cannabis is legal to be screened for the drug, for the health of both mother and baby, by scientists who published a new national study.

The research shows pregnant women were around 4.6 times more likely to report using cannabis, where it is legal for medical and recreation, compared to where CBD is only allowed.

A sizeable proportion of women reported using the drug for medical purposes, which is in keeping with “a growing body of evidence” that suggests in order to alleviate pregnancy symptoms cannabis is being used as a substitute for medical drugs in legalised areas.

“Therefore it is increasingly important to evaluate the risk-benefit profile of cannabis as compared to other medical treatments to understand any potential therapeutic indications for cannabis use in pregnancy,” says lead author Kathak Vachhani, who was a student in the Keenan Research Summer Student Program at St. Michael’s Hospital, a site of Unity Health Toronto, when the research was conducted.

The team is calling for prenatal and primary care providers to screen and counsel patients regarding cannabis use in pregnancy, particularly in states where it is legal, for the potential effects on foetal development.

They also state public messaging “around the risks” of cannabis in pregnancy is “particularly relevant now,” as many states have recently implemented cannabis laws and established cannabis markets.

The legalisation of cannabis products has increased exponentially in the last decade in the United States. The legalization has been piecemeal, states variously allow the use of cannabidiol (CBD) products, the use of medically prescribed cannabis, the use of cannabis for recreational purposes, or some combination thereof.
While the use of these products has risen among all demographics, among the least studied sector are pregnant women. Because cannabis has been known to be used to treat some symptoms associated with pregnancy—notably nausea and vomiting, the use is on the increase.

While previous studies have examined the use of cannabis by pregnant women in restricted geographic areas and under particular legislative parameters, this study involved a broader dataset to compare use across legalisation frameworks in 27 states.

The authors found self-reported use was “significantly higher” in pregnant women residing in states that allow medical and adult use, compared to those residing in states with restricted use.

Most respondents who reported cannabis use smoked it partially or mostly for recreational purposes. “Mode of intake and reason for consumption did not differ between state groups,” the authors observed.

Previous studies have shown that medical cannabis usage during pregnancy can be effective for nausea and vomiting. Medical cannabis may be suitable to treat pregnancy-specific conditions which, if untreated, could be more harmful to the foetus than cannabis.

However, safe usage depends on having a comprehensive understanding of the benefits and risks of cannabis when weighed against the risks of untreated or refractory conditions such as hyperemesis gravidarum.

Therefore, more research is needed, said Vachhani.

“Cannabis is a complex substance and its use is further complicated by factors such as the form of intake and frequency of use.

“From the mother’s health standpoint, our current understanding is rudimentary regarding the complex interplay between use (whether CBD or THC-based) and long-term health outcomes for the mother.

“There is currently no accepted therapeutic indication or safe amount of cannabis that may be consumed during pregnancy.

“Although further studies may lead to an accepted therapeutic indication, based on the current consensus the positive association between cannabis use and legalisation found in our study warrants further inquiry.”

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