Pregnancy after Haematopoietic Stem Cell Transplant: an international multicentre study

Maintenance of fertility is important to patients undergoing haematopoietic stem cell transplant because many are of childbearing age and treatment is frequently sterilising. Pre-transplant fertility preservation counselling is currently limited by a paucity of data. Pregnancy post-transplant is an infrequent event and while small studies provide anecdotal information, interpretation of larger data sets can be confounded by lack of detail. In this multicentre study, patients transplanted between January 1995-December 2015 who subsequently became pregnant/partners became pregnant, were identified by centres 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 transplanted patients, there were 621 pregnancies among 419 patients/partners, and 581 live births. There was substantial variation in likelihood of pregnancy following 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 following allografts using total body irradiation and lowest following 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 post-transplant and preservation of gonadal function, however our data highlight multiple factors relevant to contemporary pre-transplant counselling and fertility preservation services.