In Utero Hematopoietic Stem Cell Transplantation for Alpha-thalassemia Major (ATM)

Inclusion Criteria: * Male or female fetuses from 18 weeks and 0/7 days to 26 weeks 0/7 days gestation with a diagnosis of alpha-thalassemia major by chorionic villus sampling (CVS), amniocentesis, cordocentesis or by identification of parents as genetic carriers, and identification of fetal anemia or signs of impending hydrops, for whom parents elect to pursue in utero transfusion, and are willing to undergo subsequent IUT for the remainder of gestation. * parents must consent to fetal autopsy in the event of a fetal demise * adequate bone marrow harvest from maternal participant is a condition for inclusion Exclusion Criteria: * Fetal Subject Exclusion Criteria: Fetal participants will be excluded if they have a second major anatomic anomaly (not related to the underlying thalassemia) that contributes a significant morbidity or mortality risk, or echocardiogram or ultrasound findings that indicate a high risk of fetal demise after fetal intervention. * Maternal Subject Exclusion Criteria: Maternal participants will be excluded if they have one or more morbidities that would preclude bone marrow harvest and fetal intervention including, but not limited to, morbid obesity with BMI \> 35, maternal cardiac disease, mirror syndrome, symptomatic maternal anemia, or if they develop preterm premature rupture of membranes (PPROM) or active preterm labor (PTL).