NIH Press Release
National Institute on Drug Abuse

Friday, Oct. 11, 1996

Mona Brown
Sheryl Massaro
(301) 443-6245

Early Pregnancy Halted By Chemicals in Marijuana

Scientists have determined a link between activation of the biological receptors that respond to cannabinoids, the psychoactive ingredients in marijuana, and abrupt interruption of pregnancy at a very early stage. Research funded by the National Institute on Drug Abuse (NIDA) and the National Institute on Child Health and Human Development, both of the National Institutes of Health, suggests that exposure of embryos to the cannabinoids can often prevent the embryos from attaching to the uterine wall.

"This research adds to the growing body of evidence on the serious and harmful effects of marijuana, which many people mistakenly believe is a 'safe' drug," said Dr. Alan I. Leshner, Director of NIDA.

In studies conducted on mouse embryos, University of Kansas scientists Zeng-Ming Yang, B. C. Para, and S. K. Day first demonstrated that, when the cannabinoid receptors were activated in the embryos, embryonic development usually ended on or before the eight-cell, or 3-day stage. When a compound was added to block activation of the receptors, the scientists found the embryos developed normally.

This research is reported in the October issue of the Journal Biology of Reproduction, published by the Society for the Study of Reproduction.

NIDA is the primary Federal agency responsible for the conduct and support of research to increase knowledge and develop strategies to deal with the health problems and issues associated with drug abuse and addiction.

For additional information on this study and other NIDA research, call the NIDA Press Office at (301) 443-6245. Copies of NIDA Media Advisories and other information are available on the NIDA Home Page at