FDA pregnancy category C. It is not known whether Ritalin will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication. Methylphenidate has been assigned to pregnancy category C by the FDA. Adequate animal reproductive studies to establish the safe use of methylphenidate during pregnancy have not been conducted. There are no controlled data in human pregnancy. However, in the Michigan Medicaid Birth Defects Study involving 229,101 pregnancies from 1985 to 1992, there was one major cardiovascular birth defect reported out of 13 newborns who were exposed to methylphenidate during the first trimester. (One was expected.) (Written communication, Franz Rosa, MD, Food and Drug Administration, 1994) Methylphenidate is only recommended for use during pregnancy when benefit outweighs risk.