Can Smoking Weed Cause a Miscarriage?

With cannabis being legalized for recreational and medicinal use in the vast majority of states, many women are wondering: can smoking weed cause a miscarriage?


Cannabis use during the time of conception and very early in pregnancy may cause the fertilized egg from passing through the fallopian tube to the uterus, according to research done by Vanderbilt University.

Right after conception, a woman has no idea she is even pregnant. The woman assumes that she never conceived and is just having her period. She never realizes that she is, in fact, experiencing a very early miscarriage (here’s what a miscarriage is like at six weeks).

Ectopic Pregnancy and Impaired Fertility

The same research done by the Vanderbilt University revealed that tetrahydrocannabinol (THC), which is what is responsible for the ‘high’ attained by smoking marijuana, may play a key role in impaired fertility. It is also believed to be a factor in ectopic pregnancies.

Understanding how THC Interacts With the Body During Pregnancy

THC binds to the body’s CB1 and CB2 receptors. The receptors are located not only in the brain but also in a woman’s eggs and newly formed embryo. The molecule anandamide.activates the receptors in the body naturally.

Anandamide in the woman’s body reacts with the enzyme NAPE-PLD. Together they create a careful balance with the enzyme FAAH. Without this balance, an embryo will not develop properly and will be unable to be transported normally along the oviduct to develop in the uterus into a full term pregnancy.

THC swamps the receptors and disrupts anandamide in the woman’s body. This creates an imbalance in FAAH which causes high incidences of impaired fertility from early miscarriage and ectopic pregnancies.

Cannabis and Fertility

Cannabis use has a direct effect on a woman’s luteinizing hormone (LH) which is secreted by her pituitary gland.  Using marijuana causes a decrease in the LH hormone by as much a 50 to 80 percent.

The decrease in the LH levels caused women to cease ovulation completely which impaired their fertility. It is believed that such an effect is short term and as the woman builds up a tolerance to the long-term use of cannabis her LH levels return to normal and she resumes ovulation.

Turning to Medicinal Marijuana for Morning Sickness

Cannabis has many undeniable health benefits. For years it has been used by cancer patients undergoing chemotherapy to battle the often debilitating effects of nausea.  In states where it has been legalized for recreational use, many pregnant women are turning to a few puffs of weed in the mornings to alleviate morning sickness.

Unfortunately, the concrete scientific research still does not exist to reveal if cannabis use during pregnancy causes miscarriage during the first, second, or third trimesters.

THC Crossing the Placental Barrier

It is known that THC and other cannabinoids found in cannabis can cross the placenta and enter the fetus which may cause problems later in the child’s development. Studies have shown that the brains of fetuses at 18 to 22 weeks were affected by THC exposure.

Researchers noted that the fetuses showed abnormalities in the amygdala region of the brain that control emotions. However, research has not shown an increase in miscarriages by cannabis users later in pregnancy despite the ability of THC and other cannabinoids to cross the placental barrier.

Cannabis Might Contribute to Low Birth Weight, Preterm Delivery, and Increased Admission to the NICU

In research done by the School of Population Health at The University of Queensland in Brisbane, Australia it was found that cannabis use during pregnancy resulted in low birth weight, preterm delivery, and increased admission to the NICU. The study was done on  24,874 pregnant women.

It was found that 2.5 percent gave birth to babies with a low birth weight, 1.5 percent experienced preterm deliveries, and 2.5 percent had babies that required immediate admittance into the NICU for a variety of reasons. It is believed that those increases could have been prevented if the pregnant women who participated in the study did not use cannabis during pregnancy.

Marijuana Usage During Pregnancy

It is estimated that 2 to 27 percent of women use marijuana during their pregnancy. However, the true number is difficult to determine because cannabis use remains unreported, especially in states where marijuana remains illegal.

Cannabis Use and Miscarriages in Jamaica

In the United States, research remains limited when it comes to miscarriages and cannabis use. For years, marijuana was labeled an illegal drug. Only recently has it become legal for recreational use in many states so studies still need to be done by scientists and medical researchers to determine the role marijuana use plays in miscarriage.

However, in Jamaica marijuana use is widespread and has been accepted for years. Research done in the 1980s by Dr. Melanie Dreher found that miscarriages among cannabis users did not increase but remained on par with the global average.

More Research on Cannabis Needed

For years, tobacco use has been shown to cause miscarriages, however, research showing that smoking weed causes miscarriage remains lacking. Scientists and researchers have proven that cannabis can contribute to the failure of the fertilized embryo to successfully implant in the uterus, ectopic pregnancy, fertility problems, low birth weight, and preterm delivery.

What the Experts Say

“There is an increased perception of the safety of cannabis use, even in pregnancy, without data to say it’s actually safe.”

Dr. Torri Metz, an obstetrician at Denver Health Medical Center who specializes in high-risk pregnancies

We found that cannabis doubled the risk of men under 30 having poor sperm – statistically it jumped out of the analysis. I think it’s a real effect, and it’s not been shown before in such a robust way.”

Dr. Allan Pacey

“Alcohol and cigarettes were legal and used during pregnancy for many years and caused untold damage to developing neonates. Marijuana as a hallucinogenic drug that is inhaled has the potential to cause all of the problems seen in both of these legal drugs. I would strongly recommend that all women using marijuana quit before attempting to get pregnant or when they learn they are pregnant.”

Aaron Caughey, MD, chair of the Department of Obstetrics and Gynecology at Oregon Health & Science University in Portland, Oregon

“As marijuana becomes decriminalized and more accepted by society, many women mistakenly take this as a sign that it may be safe to use in pregnancy.”

Jason James, M.D., medical director at Miami’s FemCare Ob-Gyn

“There is a lot of messaging on the Internet saying that marijuana is safe to use during pregnancy, while it is actually not. Women need to know that health-care providers can recommend other morning-sickness treatments that don’t carry the risks of marijuana.”

Dr. Maya Nader, a family physician at St. Michael’s Hospital in Toronto


Sadly, one in five pregnancies will result in miscarriage but it remains unknown if cannabis use truly plays a role in increasing the likelihood of miscarriage.

Until more research is done, it is advisable that pregnant women or women trying to conceive abstain from cannabis use without first consulting with their physician.

Further Reading


Kimberly Sharpe

Based in Florida, Kimberly Sharpe has been a full-time writer since 2006. Her writing has a strong focus on travel, parenting, outdoor sports, gardening, health issues, pets (both domestic and exotic), home improvement, DIY, and business promos. Her work has appeared in USA Today, MORR Gear, Hipmunk, Travelocity, Livestrong,, Hydro Live, Maximum Yield, eHow, Yahoo News, SF Gate, Garden Guides, Whitefence, S.F. Gate,, and numerous other publications. She has traveled extensively throughout Europe, India, and Sri Lanka in an effort to expand her knowledge and enhance her writing skills.

No Comments Yet

Comments are closed

About The Toddle

We’re a media company helping parents get clearer answers to questions about raising smart, healthy kids. Get in touch to learn more about our mission.

7119 E Shea Blvd #109-176, Scottsdale, AZ 85254
(623) 226-8142