Reduced fertility among women employed as dental assistants exposed to high levels of nitrous oxide

Women who are exposed to high levels of nitrous oxide in their occupation may have a higher risk of infertility than other women. Nitrous oxide is a gas that is used as a pain killer or as a carrier gas for other anesthetics. Among 418 female dental assistants between 18 and 39 years old who had become pregnant within a four-year period, 28% had become pregnant during the first menstrual cycle of unprotected intercourse. Eighty-seven percent of the women had conceived by the end of 13 menstrual cycles. A longer period of exposure to nitrous oxide was associated with a decreased ability to become pregnant. Nineteen women who were exposed to high levels of nitrous oxide five or more hours per week were less than half as likely to conceive during each menstrual cycle as unexposed women. Exposure to high levels of nitrous oxide may interfere with the secretion of reproductive hormones in women.