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Cannabis exposure linked to unhealthy pregnancy outcomes

Researchers at the University of Utah Health have discovered a significant link between cannabis exposure during pregnancy and a heightened risk of adverse pregnancy outcomes. 

The large-scale study, involving over 9,000 pregnant individuals from various regions of the United States, marks a critical advancement in understanding the implications of cannabis use during pregnancy.

Rising cannabis use

In the past decade, the use of medical marijuana in America has more than doubled, driven by the wave of state-level legalization. 

However, despite its growing acceptance and usage as a medication, the full spectrum of health effects of cannabis, particularly on vulnerable groups like pregnant people, remains largely unexplored.

Unveiling the risks

The study conducted by experts at University of Utah Health stands out from previous research by employing more accurate methods of measuring cannabis exposure. 

This approach allows for a clearer distinction between the effects directly attributable to cannabis and those stemming from other correlated health conditions.

“Cannabis use is not safe. It increases the risk of pregnancy complications. If possible, you shouldn’t use cannabis during pregnancy,” said Dr. Robert Silver, professor of Obstetrics and Gynecology.

Confusing information

Dr. Torri Metz noted the confusion among people seeking information on the health impacts of cannabis use. 

“There’s so much information out there – discussion and social media channels and on the Internet – about cannabis use and pregnancy,” said Dr.  Metz. “I think it’s hard for patients to understand what they should be worried about, if anything.”

Key findings

The researchers found that cannabis exposure during pregnancy is linked to a 1.5 times increase in the risk of unhealthy outcomes. 

Specifically, 26% of cannabis-exposed pregnant people experienced adverse outcomes, compared to 17% among those not exposed. Notably, higher levels of cannabis exposure correlated with greater risks.

A novel approach

Unlike other studies that relied on self-reported data, which often underestimates actual usage, the researchers measured levels of cannabis metabolic byproducts in urine samples for more accurate assessments.

The team investigated a range of negative health outcomes, including low birth weight, pregnancy-related high blood pressure, stillbirth, and preterm birth. 

The strongest association was found with low birth weight. The findings raise concerns, particularly in the context of newer, more THC-concentrated cannabis products.

Broader implications 

According to the researchers, previous studies in non-human primates have found that cannabis exposure can interfere with blood supply to the placenta. The current study suggests that cannabis may disrupt the human placenta in a similar way.

Dr. Silver noted that the results are especially concerning given the high amount of THC found in newer cannabis products. These more potent products were not yet widely available when the study data was collected, and their health impacts remain largely unknown.

The researchers urge people who are considering using cannabis while pregnant to have an open conversation with their doctor. 

Dr. Silver said that continued research on the health impacts of cannabis is urgently needed so that patients can make informed decisions about their health. “As long as humans are interested in using this product, we ought to assess health effects both good and bad, as accurately as we can, and provide that information for folks.”

The study is published in the journal JAMA.

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