To determine the characteristics of pregnant women who use Ecstasy (3,4-methylenedioxymethamphetamine, MDMA), and to identify reproductive risk factors associated with this group of women. Prospective, observational study. Pregnant women who have contacted the Motherisk Alcohol and Substance Use Helpline at The Hospital for Sick Children, in Toronto, about exposure to drugs, chemicals, infection or radiation. All inquiries from December 1998 to October 2000 concerning pregnant women who reported use of MDMA, and control cases of women not exposed to MDMA selected within the same week of the MDMA callers. Age, maternal demographics, pregnancy characteristics, patterns of alcohol, tobacco, and illicit drug use, psychological/emotional status, sexually transmitted disease, MDMA method and pattern of use, and adverse drug reactions after ingestion of MDMA. The 132 pregnant women who used MDMA were significantly younger (mean 23.2 vs. 31.2 years, P<.0001), and had more unplanned pregnancies compared to 122 pregnant nonusers (84.2% vs. 54.3%, P<.05). MDMA users were also more likely to be single (57.0% vs. 18.3%, P<.001), and to be White (82.2% vs. 56.0%, P<.05). Comparably more MDMA users smoked cigarettes (53.8% vs. 19.7%, P<.0001), drank alcohol (66.4% vs. 37.3%, P<.0001), and had significantly more episodes of binge drinking during pregnancy (mean 2.12 vs. 0.05, P<.001). Illicit drugs such as cocaine, marijuana, methamphetamine, ketamine, gamma-hydroxy butyrate, and psilocybin were used more frequently among the MDMA sample. Over a third of MDMA users reported psychiatric/emotional problems, including 6.5% with a clinically diagnosed condition that was being treated with medication and/or counseling. Pregnant women who use MDMA tend to be young, single, and report psychological morbidity, and have a clustering of risk factors that may compromise the pregnancy and fetus. Smoking, heavy alcohol intake, and polydrug use, combined with a higher than expected rate of unplanned pregnancies, increases the risk of fetal exposure to potentially harmful substances. It is important to account for the range of confounding risk factors among women who use MDMA in order to define possible direct effects of MDMA in pregnancy. Now all that is technical mumbo jumbo - you need to go to a clinic and have a full check out. It need not be totally negative but expect some problems.