MARIJUANA AND PREGNANCY

For women trying to get pregnant, a marijuana joint should be one of the
farthest things from their lips, a study suggests.

According to researchers at Vanderbilt University in Nashville, Tenn.,
using marijuana at the time of conception can result in a miscarriage or a
hazardous ectopic pregnancy.

Under normal circumstances, an ovary will release an egg that becomes
fertilized by sperm, producing a multicelled embryo. The embryo then
becomes implanted in the uterus (or womb) where it grows into a fetus. The
safe passage from ovary to womb is tightly regulated by a chemical called
anandamide, which binds to "receptors" on the egg, sperm and embryo.

The trouble is that THC (tetrahydrocannabinol), the psychoactive ingredient
in marijuana, also binds to the same receptor sites and can disrupt this
delicately balanced process, lead scientist Sudhansu Dey says. In a study
of laboratory mice, the team found that THC "swamps these finely tuned
signalling systems . . . preventing the embryo's safe passage to the uterus."

As a result, the embryo fails to develop or begins to grow in the wrong
place, such as a Fallopian tube. If the ectopic pregnancy continues, it
will eventually burst the tube. Certain medications or emergency surgery
may be needed to end the pregnancy.

Women trying to conceive "should stay away from smoking marijuana," advises
Dr. Dey, whose finding were published in the Journal of Clinical Investigation.