As states have begun to legalize marijuana, its use has been more openly discussed. While the effects of other commonly used drugs, such as alcohol, have been studied extensively, the effects of marijuana – especially on developing babies during pregnancy – have been much less studied and less widely publicized. This relative silence from the scientific community has affected the public’s opinion on the safety of marijuana: 70 percent of U.S. women think there is “slight or no risk of harm” to the baby from using marijuana during pregnancy. Expectant mothers may use marijuana rather than prescription drugs during pregnancy to relieve pain because they feel “natural” or home remedies are a safer option than prescription drugs. However, just because something is “natural” doesn’t mean it is any safer or a better alternative to well-studied prescription drugs. This seems to be the case for marijuana. Given that marijuana is the most commonly used illicit drug during pregnancy, understanding its risks and impacts on the developing fetus is important.

Three large-scale longitudinal studies tracked how maternal cannabis use affected their child’s development, and they have had surprisingly consistent results. The Ottawa Prenatal Prospective Study surveyed 700 pregnant women who used marijuana in 1978 and has followed about 200 of those children into adulthood. The U.S.-based Maternal Health Practices and Child Development Study has studied 580 children of marijuana users from pregnancy through age 14. The Generation R study is tracking almost 8,000 children in the Netherlands.

Children of marijuana users were more impulsive and hyperactive, and exhibited behavioral issues, lower IQ scores, and memory problems when compared to children of non-users. These mental health problems persisted through their teenage years, where they were significantly more likely to have attention problems and depression. Marijuana-exposed children were also almost twice as likely to display delinquent behavior, such as drug use, by the age of 14 and were more than twice as likely to regularly use marijuana and tobacco as adults. The very consistent results between mice and human studies (summarized in the infographic from The Scientist below) highlights an increasing understanding of the impacts of marijuana use on development.


It’s important to note that some behavioral outcomes may not be completely related to fetal marijuana exposure. Children of marijuana users may have grown up in a different social environment with more lax views on drugs, contributing to their increased drug use.

As marijuana continues to be legalized, we should expect to see more studies on its health effects and safety.


Managing Correspondent: Chelsea Weidman Burke

Press Article: The Scientist

Original Journal Articles: The Ottawa Prenatal Prospective Study

The Maternal Health Practices and Child Development Study

The Generation R Study

Image Credit: Cleveland Public Library

171 thoughts on “How Marijuana Exposure Affects Developing Babies’ Brains

  1. I think what he did is absolutely horrendous. He must have had an ulterior motive or he would have told you the truth about what it was. Did he not want the baby? I could never forgive him for this.

  2. My sister had her newborn removed from her custody at the hospital after she gave birth because of the THC present. I hold 2 business degrees and I am very well versed in the general psychology field because of my family history and resulting research I have done to understand all of my family. Myself included. The child is now 5 and seems to be performing at an accelerated rate educationally in pre-school. His conceptual understanding and curiosity is remarkable, though it is hard to quantify exactly how comparative it is at this young age. His emotional development is on par with what you’d expect, and his behavioral demeanor is very cooperative. His environment is with me as an intellectual that structures stability as a norm for neuroplasticity reasons; I have understood for a while that stability is a key ingredient for how brains grow and accumulate experiences as knowledge reference points. Based on that fact, it genuinely does not appear to be proving that THC while carrying has a discernible impact on neurocognitive and behavioral development. He is also physically sound, active, and friendly. While this individual study certainly does not prove anything for certain, I have been watching this play out with the awareness of the possibilities on purpose. I will bookmark this page to return with updates as we go.

  3. My husband gave an edible drug, without telling me, the day before our second doctor appointment. The doctor could not find our baby heartbeat. I feel so betrayed. Do you think he was trying to kill the baby? Who gives a pregnant woman at 11weeks pregnant an edible without their consent… He told me it was a blue raspberry, and then ask me thirty minutes later how I feel. My body reacted to the drug candy and I think it caused the baby heart ti stop beating. The doctor assume it was an abnormal chromosome, cause I’m over 40 with high blood pressure.

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