Conditioning intensity and probability of live birth after blood or marrow transplantation, a BMTSS report.

We examine the impact of conditioning intensity (low intensity: nonmyeloablative/reduced intensity vs high intensity: myeloablative) and total body irradiation (TBI) on the probability of live birth after blood or marrow transplantation (BMT). Study participants were drawn from the BMT Survivor Study (BMTSS) and included 1607 transplant survivors between 1974 and 2014 at age ≤45 years, with survival ≥2 years post-BMT and age at study ≥18 years. Closest-age, same-sex biologic siblings (n = 172) were 1:1 matched with 172 survivors. Survivors and siblings self-reported information on sociodemographic, chronic health conditions, and pregnancies. Within survivor analysis: the association between the primary exposure variable (no TBI/low-intensity conditioning; 200 to 800 cGy TBI/low-intensity conditioning; no TBI/high-intensity conditioning; >800 cGy TBI/high-intensity conditioning) and the odds of no post-BMT live birth were examined using multivariable logistic regression, adjusting for clinical and demographic variables. Median age at BMT was 31 years (IQR, 0 to 45), and median length of follow-up was 14.3 years (IQR, 2.4 to 41.4); 39.3% were autologous BMT recipients, and 46.6% were female. Overall, 120 (8.7%) survivors reported post-BMT live births. Receipt of >800 cGy TBI/high-intensity conditioning (odds ratio [OR], 3.7; 95% CI, 1.9-7.0; ref: no TBI/low-intensity conditioning) was associated with higher odds of reporting no live birth post-BMT. In contrast, 200 to 800 cGy TBI/low-intensity conditioning (OR, 1.3; 95% CI, 0.5-3.3), and no TBI/high-intensity conditioning (OR, 0.9; 95% CI, 0.5-1.7) were at similar risk of reporting post-BMT live birth as no TBI/low-intensity conditioning. Comparison with biologic siblings: Using conditional logistic regression, we found that BMT survivors were more likely to report no live birth (OR, 2.0; 95% CI, 1.2-3.3) compared with siblings. These findings could inform conditioning intensity options for patients wishing to preserve fertility post-BMT.