Pregnancy after hematopoietic stem cell transplant: an international multicenter study.

Maintenance of fertility is important to patients undergoing hematopoietic stem cell transplantation (HCT) because many are of childbearing age and treatment is frequently sterilizing. Pretransplant fertility preservation counselling is currently limited by a paucity of data. Pregnancy after transplant is an infrequent event and although small studies provide anecdotal information, interpretation of larger data sets can be confounded by lack of detail. In this multicenter study, patients who received a transplant between January 1995 and December 2015 who subsequently became pregnant/partners became pregnant, were identified by centers registered with the European Society for Blood and Marrow Transplantation (EBMT). The association of pregnancy with underlying condition, transplant type, and conditioning protocols was evaluated using robust data sets from the EBMT registry. The role of assisted reproductive techniques (ART) in pregnancy were also investigated and pregnancy outcomes described. From a data set of 54 323 patients who underwent HCT, there were 621 pregnancies among 419 patients/partners, and 581 live births. There was substantial variation in likelihood of pregnancy after different conditioning protocols with highest rates in women observed after reduced intensity conditioning (RIC). ART were used by 33% of females and 56% of partners of male patients, with highest use after allografts using total body irradiation and lowest after RIC. Among females, pregnancy was more frequently associated with donor eggs than the use of their own stored eggs, embryos, or tissue. Widespread use of ART distorts the association between pregnancies after transplant and preservation of gonadal function, however our data highlight multiple factors relevant to contemporary pretransplant counselling and fertility preservation services.