Marijuana May Raise Risk of Tubal Pregnancy

Mouse study found key chemical affected ability of embryo to travel to uterus

THURSDAY, Sept. 30, 2004 (HealthDayNews) -- Marijuana may increase the risk of tubal pregnancies, according to a study on mice conducted by Vanderbilt University Medical Center researchers.

They focused on CB1, a receptor that binds delta-9-tetrahydrocannabino (THC), the main active chemical in marijuana.

In pregnant mice that lacked the gene for the CB1 receptor, the embryo failed to travel through the tube leading from the ovaries to the uterus. The same thing occurred in normal mice when the CB1 receptor was overstimulated, the researchers said.

This is the first study to describe how, in mice, the CB1 receptor regulates muscle contractions that move the embryo down the oviduct. It's still not clear whether marijuana can affect the CB1 receptor and cause tubal pregnancies in humans.

But, the researchers concluded, "our results raise caution for women of reproductive ages regarding the chronic use of marijuana for recreation or pain alleviation."

The study appears in the current issue of Nature Medicine.

Senior author Sudhansu K. Dey also expressed concern about a new anti-obesity drug, now in clinical trials, that suppresses appetite by blocking the CB1 receptor.

More information

The Nemours Foundation has more about ectopic pregnancy.

SOURCE: Vanderbilt University Medical Center, news release, Sept. 27, 2004
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