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Are There Any Risks Of Using Cannabis In Pregnancy?

cannabis safety in pregnancy
Written by Dr. Leah Zachar

Are there any risks of using cannabis during pregnancy? Is using CBD during pregnancy safe? What do the experts have to say?

Finally a clear answer to the question of what risks exist using cannabis during pregnancy.

Nearly all the information in the literature on the effects of cannabis in pregnancy have come from the users of delta 9 tetrahydrocannabinol (THC), and not cannabidiol (CBD) because the cannabis that was bought and sold up until about 10 years ago, had predominantly THC in it.

What are endocannabinoids and why are they important in pregnancy?

Cannabis produces phytocannbinoids and our bodies create endocannabinoids.  Endocannabinoids are vital for successful fertilization, growth of the fetus, and survival of the newborn.

Immediately after fertilization, the endocannabinoids guide passage of the embryo through the oviduct and then assist in successful implantation of the embryo into the uterus.  Endocannabinoids are instrumental in brain development as they help direct the undifferentiated cells to become the nerves that will eventually become the cerebrum, cerebellum, and brainstem.  After the child is born, the endocannabinoids, already present and functioning in the newborn’s brain, stimulate postnatal suckling.

Prevalence of cannabis use in pregnancy

Are there any risks of using cannabis in pregnancy?

Are there any risks of using cannabis in pregnancy?

Cannabis use in pregnancy ranges from 3-16%. There is under reporting of its use due to the stigma that remains attached to it by the medical profession, and also because cannabis remains illegal in many states.  The percentage of women who use cannabis in pregnancy progressively declines from 32% in the first trimester to 16% in the third trimester.

Barriers to measuring the benefit vs. risk of cannabis in pregnancy

It is difficult to determine the effects of cannabis on the unborn child because many mothers who use cannabis also engage in the use of alcohol, nicotine cigarettes, illicit drugs, and unhealthy lifestyle habits which may potentially jeopardize the health of the newborn.

In many cases, because of the problems caused by these drugs and the unhealthy lifestyle habits, the mother seeks out cannabis for self-treatment.

Cannabis & Structural Abnormalities in the Neonate

In two well-performed prospective studies, no association was found between cannabis use and structural abnormalities. (Linn et al 1983 n=1246) (Gibson et al 1983)

In one carefully done retrospective study, no association was found between cannabis use and neural tube defects.  (Shaw et al  1996)

Cannabis & Preterm birth

No association was seen in several studies that were conducted comparing the duration of the use of cannabis in pregnancy with the length of the pregnancy.  (Freed et al 1980  n=291), (Higson et al 1982  n=1690) (Zuckerman et al 1989 n=1226) (Linn et al 1983  n=1246).

Multiple prospective cohort studies and secondary analyses have failed to provide a definitive answer regarding the incidence of preterm birth.  However, most of the studies performed suggested the absence of an increased risk of preterm birth with cannabis use.

Cannabis and Neurodevelopment

In persistent heavy users of cannabis, there were subtle effects observed in memory, language, IQ, focus, impulsivity, hyperactivity, behavioral problems, delinquency, executive functions, and depression.  However, when considering all the confounding variables, (such as concurrent alcohol use, opioid use, tobacco use, & illicit drug use) there appeared to be no association between cannabis use and neurodevelopment.

In the only prospective study to-date, there was no association between cannabis use and normal brain development: forty-four Jamaican children were followed from birth to age five.  Throughout pregnancy, twenty-four mothers used cannabis and twenty mothers did not.  The children that were born to these mothers were all assessed serially from the day they were born until age five.  No differences were seen in their developmental testing outcomes.

American College of Obstetrics & Gynecology (ACOG)

ACOG discourages all use of cannabis during pregnancy.  The main reason is because there is an absence of governmental regulation. As a result of this, cannabis consumed by the public does not have appropriate federal oversite.  Unfortunately, the absence of FDA approval also results in a lack of funding and support for the much-needed clinical trials needed to further our knowledge in cannabis use during pregnancy.

Expert Opinion

Cannabis in pregnancy: what do the experts have to say?

Cannabis in pregnancy: what do the experts have to say?

Professor Orna Diav-Citrin, M.D., works at the Ministry of Health in Jerusalem, Israel. She has an expertise in Epidemiology & Clinical Pharmacology.  She has already published 67 articles which have been cited 3,199 times.  In a lecture she gave at the 3rd International Medical Cannabis Conference held in Tel-Aviv October 2018 (which I attended), she discussed the use of cannabis during pregnancy and the health of the newborn.

Dr. Citrin explained that because all the studies to date have been performed on cannabis with THC, no conclusions can be drawn about the safety of CBD.  However, the expert opinion is that CBD is safe.

 Take home points: 

  • Cannabis is the safest way to treat many of the medical issues that a pregnant mother must deal with during her pregnancy, such as morning sickness, depression, anxiety, insomnia, mood swings, digestive issues, back pain, and fatigue.
  • If cannabis is used regularly while pregnant, 2nd and 3rd trimester ultrasounds should be performed to assess fetal growth.
  • CBD has never been studied exclusive of THC. However, expert opinion finds there to be little/no concern over using CBD while pregnant.  Further studies are indicated.
  • So, what can a pregnant woman take that is absolutely safe? Water (and maybe CBD).  Everything else – food, nutritional supplements, vitamins, herbs, and medications must all be evaluated as to their safety on a case-by-case basis.

Read next: Cannabis And Pregnancy, The Real Story: Getting Pregnant & Fertility (part 1)


“Maternal Marijuana Use and Adverse Neonatal Outcomes: A Systematic Review and Meta-analysis.”   Obstetric Gynecol. 2016 Oct;128(4):713-23.

Prenatal marijuana exposure and neonatal outcomes in Jamaica: an ethnographic study.”, Pediatrics. 1994 Feb;93(2):254-60.

 Prenatal marijuana exposure and intelligence test performance at age 6.”, J Am Acad Child Adolescent Psychiatry. 2008 Mar;47(3):254-63.

 Identifying prenatal cannabis exposure and effects of concurrent tobacco exposure on neonatal growth.”, Clin Chem. 2010 Sep;56(9):1442-50.

 “ACOG Committee Opinion.” The American Collee of Obstetricians & Gynecologists  #722, October 2017

 Maternal smoking, drinking or cannabis use during pregnancy and neurobehavioral and cognitive functioning in human offspring.”, Neurosci Biobehavioral Rev. 2006;30(1):24-41.

 Cannabis, the pregnant woman and her child: weeding out the myths.”, J Perinatology. 2014 Jun;34(6):417-24.

 Molecular mechanisms of maternal cannabis and cigarette use on human neurodevelopment.”, Eur J Neurosci. 2011 Nov;34(10):1574-83.

 Chronic toxicology of cannabis. Clin Toxicology (Phila). 2009 Jul;47(6):517-24.

 It’s not your mother’s marijuana: effects on maternal-fetal health and the developing child., Clin Perinatology. 2014 Dec;41(4):877-94.

Maternal tobacco, cannabis and alcohol use during pregnancy and risk of adolescent psychotic symptoms in offspring.”, Br J Psychiatry. 2009 Oct;195(4):294-300.

“Safety and Toxicology of Cannabinoids.”  Neurotherapeutics. 2015 Oct; 12(4): 735–746.

 “Cannabis use during pregnancy: Pharmacokinetics and effects on child development.” Pharmacol Ther. 2018 Feb;182:133-151.

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About the author

Dr. Leah Zachar

Dr. Leah Zachar, M.D. is a physician who worked for nearly thirty years in Internal Medicine.
She currently is a scientific adviser to CBD Testers. Dr. Zachar believes that there is much that medical cannabis, and cannabidiol in particular can offer to traditional medicine.