Cannabis is the most commonly used illicit drug among women of reproductive age or by women who are pregnant.
It is difficult to be certain about the specific effects of cannabis on pregnancy and the developing fetus, in part because those who use it often use other drugs as well, including tobacco, alcohol, as well as the influence of social and genetic factors13, and ethical and practical problems in conducting prospective longitudinal studies. We don’t know enough yet to be certain about all of the possible risks. We do know that THC, the psychoactive component in cannabis, crosses the placental barrier and is secreted into breastmilk of nursing mothers8. This raises important concerns about the potential impact of maternal cannabis use on the developing child, so to be safe, it is strongly recommended that pregnant and breastfeeding mothers do not use cannabis.
Can cannabis use affect fertility?
Heavy use of cannabis has been linked to decreased fertility in both men and women. In women, there is evidence that cannabis use may disrupt the menstrual cycle. In men, a number of studies have found a connection between cannabis use and reduced fertility in men7. Men who smoke cannabis frequently have significantly less seminal fluid, a lower total sperm count, and their sperm behave abnormally, all of which may affect fertility adversely. Cannabis use can also disrupt in vitro fertilization (IVF) procedures, resulting in fewer eggs retrieved and lower chance of fertilization. In one study, women smoking cannabis 1 year before attempting IVF had 25% fewer eggs retrieved and fewer fertilized16. These factors can make it difficult for a woman to become pregnant.
Can cannabis use affect pregnancy?
THC is known to pass from the mother to the developing fetus through the placenta24. This means that the fetus is affected by any amount of cannabis taken by the pregnant woman, placing it at a greater risk of complications occurring. Secondhand cannabis smoke may result in illness or altered consciousness in infants and young children25. The effect of the passive inhalation of cannabis as a result of breathing in the smoke of others is not quantified, but has been associated with altered consciousness in the infant25 and should be avoided. Any form of smoking can disrupt the supply of oxygen and nutrients to the fetus, which can result in restrictions in the growth of the fetus including overall length, foot length, head size and body weight13.
Mothers using cannabis to treat medical conditions, like chronic pain, should discontinue use while they are pregnant until more information about the potential harms is available. While the use of cannabis appears to relieve reported symptoms of nausea during pregnancy (though it didn’t impact the rate of vomiting)4, women should be aware of the fact it has unproven fetal safety and other treatments for morning sickness may be safer. Although cannabis has not been implicated as an agent that causes birth defects17, there is evidence for adverse neuro-developmental effects after prenatal exposure5,9.
Can cannabis use affect the baby?
Adverse fetal outcomes related to cannabis use during pregnancy remain unclear. There is some evidence, however, that women who use cannabis during pregnancy are more likely to experience placental complications21 and give birth to babies with lower birth weight14,12; temporary poor autonomic control, particularly in terms of regulating their alertness19; and a “hole in the heart”(ventricular septal defect)23.
Research suggests that, at ages three to four years, children of mothers who used cannabis while pregnant have poorer verbal, memory and reasoning ability; poorer motor skills and shorter length of play; and are more likely to be fearful, impulsive, inattentive, hyperactive and delinquent6. These difficulties appear to persist into adolescence, when they may be accompanied by increased depression and anxiety, along with reading and spelling problems and general underachievement at school6. Such deficits may also continue into early adulthood, along with an increased risk for initiation of tobacco and cannabis use19,20.
In addition, there exists some evidence that mothers’ cannabis use during pregnancy increases the risk of their children developing childhood cancers, including non-lymphoblastic leukemia, rhabdomyosarcoma (a rare, highly malignant tumor that can occur anywhere in the body), and astrocytoma (a type of brain tumor)11.
Preliminary research suggests that fathers’ cannabis use in the year prior to their children’s birth is associated with an increased risk of rhabdomyosarcoma in their children10, and that fathers’ cannabis use during conception, pregnancy, or post-natally may be associated with an increased risk of Sudden Infant Death Syndrome (SIDS) in their infants15.
Can cannabis use affect breast milk?
When a breastfeeding mother uses cannabis, THC passes into the breast milk and thus into the baby, where it can be stored in the baby’s fatty tissue for several weeks. Infants exposed to THC through breast milk experience increased tremors, poor sucking, slow weight gain, and poor feeding in the first month of life18,22. Studies have also suggested cannabis exposure through breast milk could decrease motor development of the child at one year of age8, but little is known for sure about the adverse effects of postnatal cannabis exposure through breastfeeding because of a lack of studies in lactating women.
More research is needed to be certain of the risks to infants from breast milk containing THC, and the American Academy of Pediatrics has recommended that women avoid breastfeeding it they consistently or heavily use cannabis1,2.
Concerned about your or your partner’s use?
A woman planning to become, or already pregnant, and her partner are both advised to stop using cannabis and to talk to a health care provider openly about past use and the potential risks of continued use. Your health care provider needs a complete history in order to best provide you with the care you, your partner, and your baby need. They will also be able to help, or refer you to someone else who can help, you or your partner cut down or quit cannabis use.
- American Academy of Pediatrics (AAP). Policy statement: Breastfeeding and the use of human milk. Pediatrics 2012;129(3):e827-e841. View abstract
- American College of Obstetricians and Gynecologists (ACOG), Committee on Obstetric Practice: Committee Opinion on Marijuana use During Pregnancy and Lactation. Number 637, July 2015. Free online
- Campolongo P, Trezza V, Ratano P, et al. Developmental consequences of perinatal cannabis exposure: behavioral and neuroendocrine effects in adult rodents. Psychopharmacology 2010;214(1), 5–15. Free online
- Chandra K, Ho E, Sarkar M, et al. Characteristics of women using marijuana in pregnancy and their reported effects on symptoms of nausea and vomiting of pregnancy: A prospective, controlled cohort study. J FAST Int 2003;1:e13. Free online
- Dahl RE, Scher MS, et al. A longitudinal study of prenatal marijuana use. Effects on sleep and arousal at age 3 years. Arch Pediatr Adolesc Med 1995;149:145-50. View abstract
- Faden VB, Graubard BI. Maternal substance use during pregnancy and developmental outcome at age three. J Subst Abse 2000;12(4):329-40. View abstract
- Fronczak CM, Kim ED, Barqawi AB. The insults of illicit drug use on male fertility [Review]. Journal of Andrology 2012;33(4):515-528. Free online
- Garry A, et al. Cannabis and breastfeeding. J Toxicol 2009;2009:596149. View abstract
- Goldschmidt L, Day NL, et al. Effects of prenatal marijuana exposure on child behavior problems at age 10. Neurotox Teratol 2000;22:325036. View abstract
- Grufferman S, et al Parents’ use of cocaine and marijuana and increased risk of rhabdomyosarcoma in their children. Cancer Causes Control 1993;4(3):217-24. View abstract
- Huang YH, et al. An epidemiologic review of marijuana and cancer: an update. Cancer Epidemiol Biomarkers Prev.2015;24(1):15-31. View abstract
- Huizink AC. Prenatal cannabis exposure and infant outcomes: overview of studies. Prog Neuropsychopharmacol Biol Psychiatry 2014;52:45-52. View abstract
- Jaques SC, et al. Cannabis, the pregnant woman and her child: Weeding out the myths. Journal of Perinatology 2014;34:417-424. View abstract
- Janisse JJ, Bailey BA, Ager J, Sokol RJ. Alcohol, tobacco, cocaine, and marijuana use: relative contributions to preterm delivery and fetal growth restriction. Subst Abuse 2014;35(1):60-7. View abstract
- Klonoff-Cohen H, Lam-Kruglick P. Maternal and paternal recreational drug use and sudden infant death syndrome. Arch Pediatr Adolesc Med 2001;155(7):765-770. View abstract
- Klonoff-Cohen HS, Natarajan L, Chen RV. A prospective study of the effects of female and male marijuana use on in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) outcomes. Am J Obst Gynecol 2006;194(2):369-76. View abstract
- Lee MJ. Marihuana & tobacco use in pregnancy. Obst Gyn Clin N Amer 1998;25(1):65-81
- Miller CW. Marijuana use and breastfeeding. Clinical Lactation 2012;3-3:102-107. Free online
- Minnes S, Lang A, Singer L. Prenatal tobacco, marijuana, stimulant, and opiate exposure: outcomes and practice implications. Addict Sci Clin Pract. 2011;6(1):57–70. Free online
- Sonon KE, Richardson GA, Cornelius JR, Kim KH, Day NL. Prenatal marijuana exposure predicts marijuana use in young adulthood. Neurotoxicol Teratol 2015;47:10-5. View abstract
- Warner TD, Roussos-Ross D, Behnke M. It’s not your mother’s marijuana: effects on maternal-fetal health and the developing child. Clin Perinatol 2014;41(4):877-94. View abstract
- Washington State Dept. of Health. Substance Abuse During Pregnancy: Guidelines for Screening and Management, rev. 2015.
- Williams LJ, Correa A, Rasmussen S. Maternal lifestyle factors and risk for ventricular septal defects. Birth Defects Res A Clin Mol Teratol 2004;70(2):59-64. View abstract
- Wu CS, Jew CP,Lu, HC. Lasting impacts of prenatal cannabis exposure and the role of endogenous cannabinoids in the developing brain. Future Neurology 2011;6(4): 459–480. Free online
- Zarfin Y, Yefet E, Abozaid S et al. Infant with altered consciousness after cannabis passive inhalation. Child Abuse Negl 2012; 36(2), 81–83. View abstract