Marijuana Use and Pregnancy

What’s the Problem?

As more states legalize medical and recreational marijuana, some pregnant women have turned to using marijuana to ease nausea or other pregnancy symptoms. However, researchers don’t know a lot about what the effects might be and while the research is in progress, most experts advise pregnant women not to use marijuana.

Many of the chemicals in marijuana (in particular, tetrahydrocannabinol or THC) can pass through a mother’s system to her baby and can negatively affect a baby’s health.1-7 Research shows that using marijuana while pregnant can cause health problems in newborns—including low birth weight.1-7 Using marijuana during pregnancy may also increase a baby’s risk of developmental problems.1-7

Use of synthetic marijuana (known as fake weed, K2 or Spice) is also potentially harmful to a baby’s development. Spice products contain extremely high THC equivalents, which can affect a baby’s birth weight and size.8 Breathing marijuana smoke can also be bad for a mother and her baby. Marijuana smoke has many of the same chemicals as tobacco smoke and may increase the chances for developmental problems in a baby.10-11

Who’s at Risk?

About 1 in 25 women in the United States report using marijuana while pregnant.9

Can It Be Prevented?

The good news is that prenatal marijuana exposure is completely preventable. Any woman who is pregnant or could become pregnant should avoid consuming marijuana.

Healthcare providers can routinely talk to women who are pregnant, planning to get pregnant, or could become pregnant about their marijuana use and advise them on the dangers of marijuana use during pregnancy and in general.

Tips for Scripts

It is important to include accurate information about the health risks of using marijuana for a mother and her baby. Some important ideas to convey include,

  • marijuana use during pregnancy may increase your baby’s risk of developmental problems;
  • the chemicals in any form of marijuana may be bad for your baby (this includes edible marijuana products such as cookies, brownies, or candies);
  • marijuana use during pregnancy may negatively impact your baby after birth (research shows marijuana use during pregnancy may make it hard for your child to pay attention, learn, or do well in school and these issues may only become noticeable as your child grows older); and
  • if you’re using marijuana and are pregnant or planning to become pregnant, talk to your doctor.

The Bottom Line

Mothers may put their babies at risk of health problems when they expose them to marijuana during pregnancy.

Case Example

Samantha lives in a state where marijuana is legal for medical use. She recently found out she’s pregnant with her second child.  During her first pregnancy she had a lot of morning sickness, didn’t have an appetite, and lost a lot of weight. She worried about this happening again and has heard smoking marijuana might be a good option for her. After all, it’s natural right?

Samantha goes to see her doctor who tells her that there’s very little research to support marijuana being safe, and the research that has been done suggests mothers who use marijuana while pregnant can put their babies at increased risk for health problems—including low birth weight and developmental problems. Their children may also have attention and learning problems or trouble doing well in school as they get older. Samantha’s doctor recommends she err on the side of caution by not smoking marijuana due to all the risks involved. Instead she recommends Samantha try a few things to prevent morning sickness like

  • eating as soon as she wakes up to help get something in her stomach before she starts her day,
  • aiming for a diet high in protein (such as chicken) and complex carbohydrates (such as whole grains and vegetables),
  • trying chicken soup, which will help hydrate her and provide some calories, and
  • taking medications (those with a reassuring safety record during pregnancy) she could prescribed  to control nausea and vomiting—if needed.


  1. Mark, K., A. Desai, and M. Terplan, Marijuana use and pregnancy: prevalence, associated characteristics, and birth outcomes. Arch Womens Ment Health, 2016. 19(1): p. 105-11.
  2. Fried, P.A., B. Watkinson, and R. Gray, Differential effects on cognitive functioning in 9- to 12-year olds prenatally exposed to cigarettes and marihuana. Neurotoxicol Teratol, 1998. 20(3): p. 293-306.
  3. Leech, S.L., et al., Prenatal substance exposure: effects on attention and impulsivity of 6-year-olds. Neurotoxicol Teratol, 1999. 21(2): p. 109-18.
  4. Goldschmidt, L., et al., Prenatal marijuana exposure and intelligence test performance at age 6. J Am Acad Child Adolesc Psychiatry, 2008. 47(3): p. 254-63.
  5. Campolongo, P., V. Trezza, P. Ratano, M. Palmery, and V. Cuomo, Developmental consequences of perinatal cannabis exposure: behavioral and neuroendocrine effects in adult rodents. Psychopharmacology (Berl), 2011. 214(1): p. 5–15.
  6. Warner, T.D., D. Roussos-Ross, and M. Behnke, It’s not your mother’s marijuana: effects on maternal-fetal health and the developing child. Clin Perinatol, 2014. 41(4): p. 877-94.
  7. Colorado Department of Public Health and Environment. Monitoring Health Concerns Related to Marijuana in Colorado: 2014. 2015.
  8. Delphine Psychoyos, K. Yaragudri Vinod. Marijuana, Spice ‘herbal high’, and early neural development: implications for rescheduling and legalization. Drug Testing and Analysis, 2012.
  9. Ko JY, Farr SL, Tong VT, Creanga AA, Callaghan WM. Prevalence and patterns of marijuana use among pregnant and nonpregnant women of reproductive age. Am J Obstet Gynecol. 2015; 213(2):201.e1-201.e10.
  10. Wu, T.C., et al., Pulmonary hazards of smoking marijuana as compared with tobacco. N Engl J Med, 1988. 318 (6): p. 347-51.
  11. Gunn JKL, Rosales CB, Center KE, et al. Prenatal exposure to cannabis and maternal and child health outcomes: a systematic review and meta-analysis. BMJ Open 2016;6:e009986.doi:10.1136/bmjopen-2015-009986.
Page last reviewed: October 6, 2017