Herbert Schuel, PhD, Professor Emeritus of Anatomy and Cell Biology, who presented his research into marijuana's effect on reproduction at the annual meeting of the American Society for Cell Biology, stated in a Dec. 12, 2000 BBC News article:

“We know that sperm capacitation and fertilising potential are tightly regulated within the female reproductive tract.

Within the uterus, anandamide [a naturally occurring endogenous cannabinoid neurotransmitter found in the brain, which is sensitive to the cannabinoids in marijuana] regulates early development of the fertilised egg, and determines where the embryo will implant to initiate pregnancy. Cannabinoids also affect this process…

The increased load of cannabinoids in people who abuse marijuana could flood natural endocannabinoid-signal systems in reproductive organs and adversely impact fertility.”

Dec. 12, 2000