To give guidance about pregnancy safety, FDA requires that manufacturers include in the professional labeling for each drug which one of several categories, reflecting information from studies available at the time the label was developed. The benefits of its use to fight life-threatening cancers may outweigh the potential harm to a fetus. It is highly effective for treating severe cystic acne, but it causes serious birth defects. There are other drugs available to treat acne, and the disease is not life-threatening to the mother. It's important for pregnant women to realize that most birth defects are not caused by a single factor, nor are they usually caused by faint traces of toxins.
Scientists believe it takes a combination of factors to trigger a congenital malformation.
Most of the chemicals a pregnant woman encounters pose little threat compared with the harm in smoking, drinking alcohol, or eating a poor diet. Public health warnings are aimed at the many to help the relatively few avoid a problem. Daily, heavy exposure to chemicals may be dangerous, however. If a pregnant woman must work around fumes or chemicals, such as in a dry-cleaning business, art studio, or factory, she should use gloves, masks and adequate ventilation. But if she just gets a whiff of dry-cleaning fluid while picking up her laundry from the cleaners, there's little need to worry, Leavitt says.