Nurses who work with chemotherapy drugs, sterilizing agents, and X-rays are at higher risk for spontaneous abortions than nurses not exposed to these hazards, finds a survey of 7,482 nurses who became pregnant between 1993 and 2002. Exposure to chemotherapy drugs doubles the risk of spontaneous abortion; sterilizing agents, such as formaldehyde, raise the risk by about 40%; and X-rays raise the risk by about 30%. Chemotherapy drugs, which target rapidly dividing cells in tumors and fetuses, are teratogenic and mutagenic. Chemotherapy drugs and X-rays are known reproductive hazards; however, the study found that nurses are still exposed during pregnancy. "We encourage nurses who are pregnant, or who wish to become pregnant, to work with their employers and their health care providers to reduce exposures during pregnancy and lactation," the researchers write in the American Journal of Obstetrics and Gynecology, published online, December 30, 2011.