Neonatal Outcomes on Direct Fetal Intravenous Immunoglobulin During Intrauterine Transfusion for Rhesus Isoimmunization

The goal of this clinical trial is to learn if giving intravenous immunoglobulin directly to the fetus during intrauterine transfusion can improve newborn outcomes in pregnancies affected by rhesus isoimmunization. Rhesus isoimmunization happens when a pregnant woman's immune system attacks her baby's red blood cells. This can cause severe anemia (low red blood cell levels) before birth. Doctors treat this condition with intrauterine transfusion, a procedure that gives blood to the fetus before birth. However, this treatment does not stop the immune attack. Many newborns still develop anemia and high bilirubin levels after birth and may need phototherapy or exchange transfusion. The main questions this study aims to answer are: Does adding fetal intravenous immunoglobulin increase the baby's blood count at birth? Does it lower the need for phototherapy or exchange transfusion after birth? Researchers will compare: Intrauterine transfusion with fetal intravenous immunoglobulin to Intrauterine transfusion alone to see if adding immunoglobulin improves newborn outcomes. Participants will: * Undergo intrauterine transfusion as part of routine care * Be randomly assigned to receive either standard transfusion alone or transfusion with added fetal immunoglobulin * Be followed until delivery and during the newborn hospital stay The main outcome is the baby's blood count at birth. Researchers will also measure: * How quickly the baby's blood count falls before birth * Need for and duration of phototherapy * Need for exchange transfusion or blood transfusions after birth * Any procedure-related complications This study will help determine whether treating the immune process before birth can improve health outcomes for newborns affected by rhesus isoimmunization.

Inclusion Criteria: 1. Rh isoimmunized mother-fetus dyads undergoing first clinically indicated intrauterine transfusion 2. Gestational age 20 weeks or more at the time of first intrauterine transfusion 3. Written informed consent obtained from parent(s) or legal guardian Exclusion Criteria: 1. Major fetal structural anomaly or chromosomal abnormality 2. Maternal contraindication to intrauterine transfusion 3. Known immunoglobulin A deficiency with anti-immunoglobulin A antibodies 4. Previous anaphylaxis to intravenous immunoglobulin 5. Severe maternal renal impairment (chronic kidney disease stage 4 or 5 or acute renal failure) 6. Multiple gestation pregnancy 7. Anticipated technical infeasibility of umbilical venous access