Teratogenic effects of antileukemic chemotherapy.

The clinical teratogenicity of the new antileukemic chemotherapeutic agents administered to mothers early in the first trimester of pregnancy is not well defined. Cytarabine and thioguanine were given in identical doses to the same mother during the first trimester of two separate pregnancies. Both pregnancies resulted in viable babies, one with and one without congenital malformations. This case illustrates the highly unpredictable clinical effects on the fetus of chemotherapy early in pregnancy.