How does smoking weed (marijuana, THC, pot, grass) effect a developing fetus?

Studies following marijuana-exposed babies have shown that they are more likely to have subtle problems that affect their ability to pay attention and to solve visual problems.

Some scientific studies have found that babies born to marijuana users were shorter, weighed less, and had smaller head sizes than those born to mothers who did not use the drug. Smaller babies are more likely to develop health problems. There are also research data showing nervous system problems in children of mothers who smoked marijuana.

But marijuana is natural, how can something that grows from the ground be harmful?

This is a really good question because marijuana does have a strong association with being natural and like an ‘herb’. However there are many natural things or things that grow out of the ground that are harmful to humans (poison oak, certain mushrooms, even the leaves of tomato plants). Also, because marijuana is inhaled, this can pose serious consequences to the woman’s lungs and the quality and quantity of oxygen delivered to the developing fetus.

Also, because illicit drugs aren’t subject to any sort of inspection or quality control, marijuana is often laced with other drugs or substances that can also be harmful to the developing fetus.

Is it OK to use during breastfeeding?

There is significant brain growth occurring during a baby’s first months of life and marijuana may alter brain cells. The fact is, we just don’t know what the long-term effects of marijuana exposure through breast milk are.  Animal studies on babies whose mothers’ milk contained THC have shown that processes needed for proper growth and development may be impaired by marijuana.

The active ingredient in marijuana, THC, is stored in mom’s fat tissues for long periods (weeks to months) and builds up in the body with continued use. Some research has shown that when a mother uses marijuana, the levels of THC in her breast milk can be eight times higher than the levels found in her blood. However, the dose received by the baby was insufficient to produce significant side effects. Marijuana is on the American Academy of Pediatrics Committee on Drugs (2001) list of Drugs of Abuse for Which Adverse Effects on the Infant During Breastfeeding Have Been Reported.

Marijuana can cause sleepiness in the baby, which can lead to slow weight gain and possibly slow overall development in the baby long term. And babies whose mothers smoke regularly have a higher risk of SIDS.

After a breastfeeding mother uses marijuana, THC is evident in her baby’s urine and stools (Perez-Reyes and Wall, 1982). Infants exposed to marijuana via breast milk will test positive in urine screens for long periods (2-3 weeks).

One study (Astley and Little, 1990) found that exposure to marijuana through their mother’s milk during the first month of life resulted in decreased motor development at one year of age. In another study of 27 infants evaluated at 1 year of age who were exposed to marijuana via breastmilk (compared to 35 nonexposed infants), no significant differences were found in terms of age at weaning, growth, and mental or motor development. Follow-up of these infants has been limited.

If you’re pregnant and have used marijuana, don’t panic. Be honest with your health care provider about your use, especially if you think you may need help to quit.