STUDY QUESTION What are the characteristics of patients with conceptions transplanted in childhood and adolescence? SUMMARY ANSWER Insemination and conception after hematopoietic stem cell transplantation (HCT) in childhood or adolescence was possible, even after myeloablative conditioning regimes, although some patients required reproductive medicine support. WHAT IS KNOWN ALREADY Preparative regimens of HCT are highly gonadotoxic, which leads to gonadal failure and pubertal development disorders. There are few population-based studies assessing the risk of future infertility in children after HCT. STUDY DESIGN, SIZE, DURATION We conducted a retrospective study to investigate natural or assisted conceptions and their outcomes in patients <18 years old before their first transplantation who received HCT between 1995 and 2016 and were in the European Society for Blood and Marrow Transplantation (EBMT) registry. Adoptions were excluded from the analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS Detailed information concerning pregnancy occurrences and outcomes were obtained by a separate questionnaire. Quantitative variables were presented as medians with their interquartile range (IQR) or range, and categorical variables were presented as frequencies and percentages. MAIN RESULTS AND THE ROLE OF CHANCE In total, 62 988 pediatric patients received a first HCT in EBMT centers between 1995 and 2016. Pregnancy was reported in 406 patients in the database. The median age at transplantation was 15.7 (range: 0.7–18) years, and the median age at declared conception was 25.0 (range: 16.3–38.8) years. Details concerning the first pregnancy and pregnancy outcome were obtained from 99 patients (24%) from the returned questionnaires. The median age at delivery or pregnancy interruption of the females was 23.0 (IQR: 20.8–27) years, with a median time after transplant of 10.7 (IQR: 6.6–15.4) years. Compared with the mean age of healthy women at their first child’s birth (29 years old), the transplanted women delivered 5 years earlier (mean: 24.3 years). In terms of conception modality, 13/25 (52%) females conditioned with total body irradiation (TBI) and 50/52 (96%) of those conditioned without TBI conceived naturally. All seven male patients who had been conditioned with TBI achieved fatherhood but required assisted fertilization or used their cryopreserved sperm. In the females, 63/70 (90%) of all conceptions resulted in a live birth, 49/63 (84.5%) were at term and 43/46 (93%) had normal birthweight. Cesarean delivery was performed in 9/61 (15%) especially in women who had received a myeloablative regimen. LIMITATIONS, REASONS FOR CAUTION In the EBMT pediatric dataset, the age at last follow-up or death was <17 years for 75% of the patients, therefore a longer follow-up for all patients would be necessary to calculate the cumulative incidence of conception for patients transplanted during childhood and allow all patients to realize their reproductive willingness/potential. WIDER IMPLICATIONS OF THE FINDINGS Reproductive health surveillance and fertility preservation counseling are important in younger transplanted patients. Our results showed that there is a window of opportunity to conceive naturally or with reproductive medicine support. STUDY FUNDING/COMPETING INTEREST(S) Funding was provided by the ‘Stiftung für krebskranke Kinder Regio Basiliensis’, Basel, Switzerland. All authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER N/A.

中文翻译：

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儿童造血干细胞移植后的妊娠和妊娠结局：EBMT 儿科疾病工作组的横断面调查

研究问题 儿童期和青春期移植受孕患者的特点是什么？总结 答案 在儿童或青春期造血干细胞移植 (HCT) 后授精和受孕是可能的，即使在清髓调理方案之后，尽管一些患者需要生殖医学支持。已知情况 HCT 的制备方案具有高度的性腺毒性，会导致性腺功能衰竭和青春期发育障碍。很少有基于人群的研究评估 HCT 后儿童未来不孕的风险。研究设计、规模、持续时间 我们进行了一项回顾性研究，以调查患者的自然受孕或辅助受孕及其结果。在 1995 年至 2016 年期间接受 HCT 并在欧洲血液和骨髓移植协会 (EBMT) 登记处登记的第一次移植前 18 岁。收养被排除在分析之外。参与者/材料、环境、方法 通过单独的问卷获得有关妊娠发生和结果的详细信息。定量变量表示为中位数及其四分位距 (IQR) 或范围，分类变量表示为频率和百分比。主要结果和机会的作用 1995 年至 2016 年间，总共有 62 988 名儿科患者在 EBMT 中心接受了第一次 HCT。数据库中报告了 406 名患者的妊娠情况。移植时的中位年龄为 15.7（范围：0.7-18）岁，宣布受孕时的中位年龄为 25.0（范围：16.3-38.0）。8年。从返回的问卷中获得了 99 名患者 (24%) 的首次妊娠和妊娠结局的详细信息。女性分娩或妊娠中断的中位年龄为 23.0（IQR：20.8-27）岁，移植后的中位时间为 10.7（IQR：6.6-15.4）年。与第一个孩子出生时健康女性的平均年龄（29岁）相比，移植的女性提前5年分娩（平均：24.3岁）。在受孕方式方面，13/25 (52%) 接受全身照射 (TBI) 的女性和 50/52 (96%) 接受全身照射 (TBI) 的女性自然受孕。所有七名患有 TBI 的男性患者都获得了父亲身份，但需要辅助受精或使用冷冻保存的精子。在女性中，63/70（90%）的所有受孕导致活产，49/63 (84.5%) 已足月，43/46 (93%) 出生体重正常。9/61 (15%) 实施了剖宫产，尤其是在接受清髓治疗的女性中。限制、谨慎的原因 在 EBMT 儿科数据集中，75% 的患者的最后一次随访或死亡年龄小于 17 岁，因此需要对所有患者进行更长时间的随访，以计算为儿童期移植的患者受孕，并让所有患者实现其生殖意愿/潜力。研究结果的更广泛意义 生殖健康监测和生育力保存咨询对年轻的移植患者很重要。我们的研究结果表明，有机会自然受孕或在生殖医学支持下受孕。研究资金/竞争利益 资金由位于瑞士巴塞尔的“Stiftung für krebskranke Kinder Regio Basiliensis”提供。所有作者都没有需要声明的利益冲突。试用注册号 不适用。