Conception and pregnancy put at risk by marijuana use

Aug 2 2006

According to new research the use of marijuana when a woman is trying to conceive or has just become pregnant, is not recommended as it endangers the passage of the embryo from the ovary to the uterus and can result in a failed pregnancy.

The researchers from Vanderbilt University say a study with mice has shown that marijuana exposure may compromise the pregnancy outcome as an active ingredient in marijuana, tetrahydrocannabinol (THC), interferes with a fertilized egg's ability to implant in the lining of the uterus.

Marijuana is the most commonly used illegal drug among women of reproductive age; it binds together two cannabinoid receptors which are found in the brain and other organs including sperm, eggs, and newly formed embryos.

As a rule these 2 receptors are activated by a naturally occurring signaling molecule, anandamide, which is carefully balanced by an enzyme resulting in a finely tuned local "anandamide tone" in embryos and the oviduct.

This balance is needed for normal embryonic development, transport along the oviduct, implantation in the uterus, and full-term pregnancy.

For the study, Sudhansu Dey, a professor of pediatrics, cell and developmental biology and pharmacology, and colleagues demonstrated that the suppression of this enzyme activity in the embryos and oviduct elevates anandamide levels, which then inhibits the entire process, causing impaired fertility.

They also demonstrated that when the mice were given doses of THC, the major psychoactive component of marijuana, the normal anandamide tone was swamped causing implantation of the embryo in the earliest stages of pregnancy to fail.

The study shows that drugs such as marijuana are able to overwhelm finely tuned signaling systems and may lead to ectopic pregnancy and/or impaired fertility in women.

Herbert Schuel from the State University of New York says the results of the study are sobering regarding marijuana's effects on pregnancy outcome.

He warns that a number of drugs currently in development or in use to suppress appetite or trigger weight-loss are also known modulators of anandamide signaling and given the results presented in the current study "such drugs need to be carefully evaluated to judge their effects on women of reproductive age and those that are pregnant."

The study appears in the August issue of the Journal of Clinical Investigation.