In 1997, the U.S. customs service seized 381,000 doses of the drug, known chemically as MDMA. Since then seizures have increased 300% to over 1 million doses.
The drug is a chemical compound made of both mescaline and amphetamine, usually found in tablet form.
A study in this week's journal Lancet shows the drug can cause birth defects if taken by women during pregnancy.
Doctors looked at 136 women, mostly in their early 20s, who used ecstasy in the first weeks of pregnancy. Fifteen percent of the seventy-eight babies who were born had birth defects, including heart problems, club feet and other deformities to the limbs.
The normal birth defect rate for women in that age group is two to three percent.
Another recent study found the drug may cause long-term brain damage.
Researchers at Johns Hopkins University found that the drug affected the production of serotonin in the brain, which can change mood, sleep and sexual activity.
Users suffered loss of memory, both verbal and visual, that persisted even weeks after they stopped using the drug. Previous studies in monkeys have found the damage to be permanent.
Ecstasy is commonly referred to as a "love" drug by young adults because it produces feelings of closeness and relaxation.
It is not considered as addictive as cocaine or heroin because the effects generally wear off in four to six hours. Health officials are concerned, however, about its long-term effects.