Cyclophosphamide is an alkylating antineoplastic agent that acts against a wide variety of oncologic and nononcologic conditions in various therapeutic categories. Intrauterine growth retardation was recorded in some cases, and it has been stated that up to 40% of delivered infants from mothers treated with antineoplastic drugs, including cyclophosphamide, have low birth weight. Abortion or early postnatal death was recorded in some of the cases, and fetal loss has been a noted characteristic in mothers treated with antineoplastic agents as a group, including cyclophosphamide. Like many other antineoplastic agents, cyclophosphamide elicits a full spectrum of developmental toxicity in animals. Cyclophosphamide is a reproductive toxicant in animals and has additionally shown male-mediated effects on development. Treating male rats in fertility-type studies with cyclophosphamide resulted in behavioral deficits in Fj offspring in one study. Cyclophosphamide is average in size compared to the other human developmental toxicants. It is hydrophilic and capable of interacting primarily as a hydrogen bond acceptor.