Few studies on effect of pot use during pregnancy

What little research there is has been contradictory

Research on the effects of marijuana use during pregnancy is scant. While it is well-documented that the developing brains of teens can be altered through regular use of marijuana, far fewer studies have been done on the long-term impact of exposure in the womb.

Research done in Pittsburgh and published in 2000 in the peer-reviewed Neurtoxicology and Teratology journal found that 6-year-olds born to a mother who had smoked one joint or more daily in the first trimester displayed less ability to comprehend concepts in reading and listening — and by age 10 they had lower reading, math and spelling scores than their peers.

It also found that children exposed to marijuana’s major psychoactive element — tetrahydrocannabinol, or THC — in the womb were more impulsive and less able to focus their attention than other 10-year-olds.

Several other studies also have found changes in the brains of fetuses 18 to 22 weeks old linked to maternal marijuana use.

A study published in the peer-reviewed American Journal of Pediatrics in 1994 found that Jamaican women who heavily smoked cannabis during their entire pregnancies had babies that early on outperformed those born to non-using mothers.

The research by Melanie Dreher, now dean of nursing at Rush Medical Center in Chicago, studied the two groups of women and then examined their babies about a year after birth. Researchers found the babies of the marijuana users socialized more quickly, were easier to engage and made eye contact more quickly.

Dreher’s study made little impression on the American College of Obstetrics and Gynecologists and the American Academy of Pediatrics. Both advise against marijuana use during pregnancy because of the studies linking it to cognitive impairment and academic underachievement. Both organizations also recommend that mothers with THC in their systems do not breastfeed.

Many researchers say the federal government’s classification of marijuana as a Schedule 1 controlled substance — the same category as heroin — has had a stifling effect on scientific study. Research-grade marijuana for federal-approved studies used to be produced by a single lab at the University of Mississippi and often took years to acquire. The U.S. government recently revised regulations to allow researchers to buy marijuana from other sources.

Contact Paul Harasim at pharasim@reviewjournal.com or 702-387-5273. Follow @paulharasim on Twitter.