Pregnant women who take certain non-steroidal anti-inflammatory drugs like aspirin and ibuprofen have an 80 percent higher risk for miscarriage, according to a recent study in the British Medical Journal. California researchers surveyed 1,055 pregnant women about their reproductive history and about their use of drugs since becoming pregnant. They found that women using NSAIDs for longer than a week at a time -- from conception up through the fourth month of pregnancy -- had the highest risk. The risk was also high in women taking them at the time of conception. Pregnant women or women planning to become pregnant should instead take acetaminophen, says study author De-Kun Li, M.D., Ph.D. Acetaminophen was found to be safe because it works only on the central nervous system, whereas other pain pills can affect the whole body, including the uterus.