Objective: The authors conducted a retrospective study of obstetric and genetic data, obstetric problems, and pregnancy outcome by investigating 149 pregnancies of patients who received genetic counselling because of hemophilia A or B over a 20-year period. Methods: In cases with a heterozygous mother, fetal sex was determined. In 23 of 35 cases with male fetuses, a DNA examination was performed. In cases with hemophilic male fetuses, the couple made a decision on whether or not to continue the pregnancy after thorough counselling regarding genetic risk. Hemophilia A occurred 135 pregnancies (98 pregnancies from 55 heterozygous mothers and 37 pregnancies from 20 hemophilic fathers). Hemophilia B occurred in 14 pregnancies (9 pregnancies from 3 heterozygous mothers and 5 pregnancies from 4 hemophilic fathers). Results: In pregnant women who were carriers of hemophilia A, 32 of the fetuses were male, and DNA examinations were performed in 22 cases. In 16 cases abortions were induced (in 10 cases hemophilia was confirmed by DNA examination), and in 4 of 16 deliveries affected males were born (the disease was confirmed by DNA examination during pregnancy). Of 3 confirmed male fetuses of heterozygous women with hemophilia B, 1 healthy male was born. In 2 cases abortions were induced (in 1 case on the basis of DNA diagnosis). Conclusions: In cases of heterozygous mothers (hemophilia A and B together) the rate of spontaneous abortions was 13.1%. The rates of premature deliveries (8.2%) and cesarean sections (8.2%) were no higher than national average. The rate of bleeding complications during pregnancy was 18.7%, in 2.7% of cases transfusions were necessary. In case of hemophilic fathers (in heterozygous female fetuses the hemostasis may change from the fetal side) the rate of bleeding complications during pregnancy was 18.2%. In terms of deliveries, obstetrical bleeding complications occurred in 12.2%, atonia in 2%, curettage after delivery in 4.1%, and transfusion in 10.2% of the heterozygous mothers with hemophilia A and B combined. Neonatal complications were cerebral hemorrhage in 1 case and bleeding from the umbilical stump in another case (both newborns were hemophilic males). In connection with delivery, there was no sign of hematoma development on the skull of the newborns, nor were transfusions necessary. In cases of paternal disease the rate of curettage was 6.7% and there were no neonatal or other obstetrical complications.