The smoke is getting thick. Marijuana use is increasing. Medical marijuana is legal in 33 states and several U.S. territories. More than a dozen other states have laws that restrict THC content (the chemical responsible for the “high”), but allow access to cannabidiol, the non-psychoactive medically active component from hemp, a plant related to marijuana.

Today, CBD products are everywhere. Public access to marijuana is different. There are many differences in state laws that govern production and how marijuana or its components can be used medically.

More lately, states have begun de-criminalizing the recreational use of marijuana. Fifteen states have decriminalized at least some aspects of marijuana use.

Recreational use of many forms of marijuana is expanding in the United States. Nine states and Washington D.C. allow recreational marijuana use, and other states will probably follow soon.

A question not discussed enough is the impact of marijuana on human health. One major area of concern is whether exposure in the womb has effects later in life.

Scientists are studying the consequences of marijuana exposure in the womb over a person’s lifetime. A recent article in, “The Scientist” reports on a large-scale human study that addressed the health impacts of marijuana use and exposure as people age.

This study also compared the effects observed on rodents over their lifetimes in lab-controlled conditions. The results are fascinating, worrisome and remarkably consistent between rodents and humans exposed to marijuana in the womb.

The study focused on mothers who smoked marijuana at least once per week during pregnancy, and it showed that marijuana exposure has an impact on the developing fetus. Newborn rodents and humans both showed a reduction in birth weight.

Human infants showed lower than average verbal reasoning scores and short-term memory. They also showed many effects including an increase in aggression, anxiety, impulsivity and hyperactivity. Experimental rodents showed similar changes. The subjects’ brains also showed chemical changes, which could begin to account for the behavioral and intellectual differences.

In adolescence, an increase in depressive symptoms and antisocial behavior have been noted in humans. Adolescent rodents showed a decrease in abstract reasoning, increased anxiety behaviors, alterations in memory and a decrease in socialization.

Frequent marijuana exposure in the womb even affects people into adulthood. Adults in the study showed a decreased ability to gather information from their surroundings visually, called visuo-spatial memory, and a significant increase in drug-seeking behaviors.

In adult experimental animals, the decrease in socialization and increased anxiety continued, with lapses in short-term memory and the connection between neuro-circuits in the brain.

We’re beginning a new era of marijuana use in the U.S. Legalization will make this psychoactive drug available to more people, and its acceptance and use is likely to increase.

That will mean more fetal exposure to marijuana and the downstream behavioral and cognitive consequences. We will need more research to understand the full range of effects and their causes. We need to have an “eyes wide open” conversation about the public health implications of marijuana use on children over their lifetimes.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at

(1) comment

Carlos Ponce

Good article! This is a topic all women of child bearing age should consider. Question: Are the negatives a result of the CBD, the THC or the combination of both? And while the article concentrates on the effects of marijuana on a developing fetus and the effects into adulthood it brings up questions about use by the general adult population.

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