Pregnancy outcome in hematologic malignancies. By means of a mail questionnaire, information on a series of 56 pregnancies i in 48 women diagnosed with leukemia or lymphoma was collected from ten hospitals. Seven patients conceived while receiving treatment for their neoplasms; in 22 patients, the hematologic disease was diagnosed during pregnancy, and the remaining 27 patients became pregnant after completion of the antineoplastic treatment. When a comparison was made of the evolution of these pregnancies to that of pregnancies in a healthy population, no increase in the incidence of complications was observed: 64% of the pregnancies went to term, 9% resulted in spontaneous abortion, and 5% resulted in premature births. The observed incidence of one major malformation in 56 pregnancies did not differ from the frequency of malformations in the offspring of healthy individuals. There were no fetal losses in six pregnancies in which conception occurred during the first year after chemotherapy. In spite of the inherent limitations derived from the design of this type of study and the type of subject analyzed, the data here support the hypothesis that the cytostatic treatment of hematologic malignancies, if deemed necessary, should not be postponed because of pregnancy. Moreover, the authors agree with advice recommending that no antifolic or alkylating agents be used for prolonged periods and that radiotherapy be avoided, especially to those fields involving the pelvic area. 