Pregnancy in women with inherited thrombocytopenias is a major matter of concern as both the mothers and the newborns are potentially at risk of bleeding. However, medical management of this condition cannot be based on evidence because of the lack of consistent information in the literature. To advance knowledge on this matter, we performed a multicentric, retrospective study evaluating 339 pregnancies in 181 women with 13 different forms of inherited thrombocytopenia. Neither the degree of thrombocytopenia nor the severity of bleeding tendency worsened during pregnancy, and the course of pregnancy was not different from that of healthy subjects in terms of miscarriages, fetal bleeding and preterm births. The degree of thrombocytopenia in the babies was similar to that in the mother. Only 7 of 156 affected newborns had delivery-related bleeding, but two of them died of cerebral hemorrhage. The frequency of delivery-related maternal bleeding ranged from 6.8 to 14.2% depending on the definition of abnormal blood loss, suggesting that the risk of risk of abnormal blood loss was increased with respect to the general population. However, no mother died or received hysterectomy to arrest bleeding. The search for parameters predicting delivery-related bleeding in the mother suggested that hemorrhages requiring blood transfusion were more frequent in women with history of severe bleedings before pregnancy and with platelet count at delivery lower than 50 x 10(9)/L.