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Is Cannabis Safe to Use During Pregnancy? New Study Clarifies Risks

October 5, 2016
background. Teenager drug abuse.

A recent review of cannabis and pregnancy studies provides new insight on a question that has long weighed on the minds of families and to-be mothers: Is cannabis safe to use during pregnancy?

Published in Obstetrics & Gynecology this month, the authors reviewed 31 studies between 1982 and 2015, evaluated their results, and concluded that cannabis – when used without tobacco or other drugs – posed no significant risks to specific concerns about birth weight and preterm delivery. This was consistent with findings of a 2010 study funded by the CDC.


Cannabis and Pregnancy: The Debates

Up until this point, studies on cannabis and pregnancy have shown somewhat contradictory results regarding birth weight and preterm delivery, a confusion that researchers attributed in part to inadequate separation of confounding variables, or factors that produce correlations even though a causal relationship doesn’t actually exist. For example, cannabis consumption and tobacco use are correlated, making it difficult to tease apart whether one or both contributes to low birth weight or preterm delivery.

The authors wrote:

“We found that maternal marijuana use during pregnancy is not an independent risk factor for low birth weight or preterm delivery after adjusting for factors such as tobacco use. There also does not appear to be an increased risk for other adverse neonatal outcomes such as SGA and placental abruption once we account for other influencing factors.”

The authors of this study concluded that cannabis use during pregnancy is still not something to be “encouraged or condoned.” Why? While this study focused on two specific birth outcomes of mothers using cannabis during pregnancy, it did not look at long-term developmental health or other risks during gestation.

A 2014 study, for example, found evidence that THC exposure during pregnancy affected brain development in both mice and humans. Fetal development is an intricate process involving specifically timed signaling that may be impacted by THC, leading to impairments later in life. Although this newest review may help relax concerns relating to birth weight and preterm delivery, there may still be other complications attributable to maternal cannabis use.

For this reason, most medical professionals still strongly recommended that pregnant women abstain from cannabis use, despite the temptation to use it for nausea and stress during the tumultuous time of pregnancy.

Bailey Rahn's Bio Image

Bailey Rahn

Bailey is a senior content manager at Leafly, specializing in strains and health. She's spent 7+ years researching cannabis products, spreading patients’ stories, and exploring healthy ways of integrating cannabis into daily life.

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  • jim heffner

    Why isn’t Doctor Dreher’s study of mothers using Cannabis in Jamaica ever considered when this question is being discussed again and again.

  • Bret Tidwell

    Unless medically necessary, I don’t believe it would be worth the risk of using any drug during pregnancy. There are so many things we just don’t know about pre-birth childhood development. I would hope that all mothers would thing long and hard before exposing a fetus to anything other than love, good food, rest and desire for the child’s maximum potential.

  • PurpleLeafStudy

    The truth is there are more women using marijuana during pregnancy than any government backed study will ever show. Which is why we are conducting our own and collecting personal stories from moms who have used marijuana for a number of reasons during pregnancy, most of whom report they would do it again. You can read more about the study here and can take the survey here .

  • Dr. Dreher’s study is definitely worth noting and I’m interested to follow the Purple Leaf Study. There are many ways to regulate the endocannabinoid system without smoking marijuana though. It’s important to educate women about this system so they can find alternative ways to get the effects of cannabis without risks: moderate excercise, eating leafy greens, acupuncture, full-spectrum hemp oil with naturally occurring CBD.