Between January 1968 and December 1992, 136 kidney transplants were performed in the University Hospital of Ribeirão Preto, with women of childbearing age (14 to 40 years) as receptors. From this population, 19 patients became pregnant at least once after transplantation, and 2 were transplanted inadvertently during the first trimester of their pregnancies. There was a total of 25 pregnancies and 27 offspring. The mean age at the time of conception was 28.6 years (23 to 41 years), with a mean interval of 3.5 years from transplant to conception (< 1 to 16 years). All patients continued their immunosuppressive regimens during the entire pregnancy, but only 5 of 25 were taking cyclosporine. There were two miscarriages (8%) and two therapeutic abortions (8%); of those that passed the 20th week of pregnancy, the mean gestation time at delivery was 35 weeks (range, 28 to 38 weeks) with an incidence of prematurity (gestation < 37 weeks) of 67%, and their offspring weighed from 670 to 3,100 g (mean, 2,236 g), presenting a very high incidence of low birthweight (64%). There was one stillborn and one neonatal death. The most common complications that occurred during pregnancy were infections (especially urinary tract and vaginal mycotic infections) followed by hypertension. The obstetric complications were distributed as follows: premature rupture of membranes in 27%, fetal distress in 24%, preterm labor in 24%, and oligohydramnios in 10%. Lower segment cesarean section was necessary in 16 of 21 cases (76%), and all were for obstetric reasons. One patient died during the puerperium because of sepsis.(ABSTRACT TRUNCATED AT 250 WORDS)