The following is one chapter from a 1997 Graduate Student Research Project conducted at the University of South Florida. The project involved locating published peer reviewed medical journal articles which have shown various environmental and chemical exposure factors can cause learning disabilities, hyperactivity and other disorders by damaging the delicate brain growth process in the unborn child during pregnancy.
INTRODUCTION
About 25% of Americans 18 to 25 years of age used marijuana to some degree according to 1980 figures from the Department of Health, Education & Welfare. Recent studies also indicate considerable marijuana use among pregnant women as well. In a study at Carleton University, Canada, by Dr. P. A. Fried, of 420 predominantly middle class Canadian pregnant women, approximately 18% of young women admitted to using marijuana to some degree before becoming pregnant, 13% were irregular users, 2% were moderate users and 3% admitted heavy use (1).
The most frequent age of marijuana use for women is also the age of childbearing. Fifty percent of 18-35 year old women reported using marijuana at least once, and 8% reported using marijuana a minimum of 10 out of the past 30 days (Clayton, R. R., Voss, H. L., Gender differences in drug use: An epidemiological perspective. In: Ray, B.; Braude, Ml, eds. Women and drugs: A new era for research. NIDA Res. Monogr. 65:80-99, 1986.) However, lower socioeconomic status appears have a significant effect on marijuana usage in women. In a 1983 random sample of 1360 women interviewed from an inner-city prenatal clinic in the Pittsburgh area, 36% of the women were moderate or heavy marijuana users (3 or more joints/day) before becoming pregnant After becoming pregnant the rate dropped to 25% by the first trimester.
Heavy marijuana use (one or more joints/day) during the first month of pregnancy averaged 20% for the first trimester but decreased to 7% for the second and third trimester in this same group. Women who used marijuana heavily during the first trimester of pregnancy did not differ from women who abstained throughout pregnancy in terms of age and education, however, they were more likely to be black and unmarried. They also had a lower income and reported more substance use during pregnancy, including alcohol, tobacco and illicit drugs other than marijuana
Regarding “any” marijuana usage before pregnancy in this sample of 1360 women, 44% reported marijuana use. This is compared to a rate of 22% reported in a general population sample by the National Institute on Drug Abuse in the 1988 national household survey on drug abuse.
The main psychoactive ingredient in marijuana, THC, crosses the placenta and has the potential for harming pregnancy outcome. Some recent epidemiological studies suggest that maternal marijuana use during pregnancy may result in perinatal hypoxia (low oxygen to the baby), premature labor, low birthweight and physical and behavior anomalies in the offspring. However, marijuana use has been difficult to measure in these reports, since it is an illegal drug, and therefore prone to under reporting, and many of the women studied also used other drugs, raising the possibility of drug interactions with marijuana.