Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started
My Medicine

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Health & Pregnancy

Font Size

How Pot Harms Fetal Brain Development

Marijuana's Key Ingredient May Hamper Nerve Cell Development
WebMD Health News
Reviewed by Louise Chang, MD

May 24, 2007 -- Scientists may have figured out how marijuana use during pregnancy harms the fetal brain.

Basically, marijuana's active ingredient, tetrahdyrocannabinol (THC), may interfere with the development of nerve cells, according to the researchers.

They included Tibor Harkany, PhD, who works in Stockholm, Sweden, at the Karolinska Institute's molecular neurobiology division.

Harkany's team studied mice and cell cultures from frogs.

According to the National Institute on Drug Abuse (NIDA), previous research has shown that some children born to women who abused marijuana during pregnancy may show signs of neurological problems in development and problems with memory and attention.

Harkany and colleagues studied a certain type of receptor in the brain. Those receptors latch onto chemicals called endocannabinoids.

The researchers explain that in a fetus, those receptors guide the development of axons, which are the long fibers of nerve cells. As the fetal brain develops, axons position themselves so they can communicate with each other.

But that process goes awry in mice with genes for impaired cannabinoid receptors. Those mice's axons didn't position themselves properly in Harkany's study. That could create communication problems between axons.

THC may mimic those effects in the fetal brain when used during pregnancy, note Harkany and colleagues. However, they didn't directly test that theory.

The study appears in the journal Science.

Pregnancy Week-By-Week Newsletter

Delivered right to your inbox, get pictures and facts on
what to expect each week of your pregnancy.

Today on WebMD

hand circling date on calendar
Track your most fertile days.
woman looking at ultrasound
Week-by-week pregnancy guide.
Pretty pregnant woman timing contaction pains
The signs to watch out for.
pregnant woman in hospital
Are there ways to do it naturally?
slideshow fetal development
pregnancy first trimester warning signs
What Causes Bipolar
Woman trying on dress in store
pregnant woman
Woman looking at pregnancy test
calendar and baby buggy
dark chocolate squares