This clinical trial is focused on studying a condition known as Fetal and Neonatal Alloimmune Thrombocytopenia, which occurs due to incompatibility between the mother’s and baby’s platelets, specifically involving a protein called Human Platelet Antigen 1. The study is investigating a treatment called RLYB212, which is a type of medication known as a human monoclonal antibody. This medication is designed to target a specific protein in the body called integrin beta-3, and it is administered as a solution through a subcutaneous injection, meaning it is injected under the skin.
The purpose of this study is to understand how RLYB212 behaves in the body during pregnancy and to ensure it is safe for both the mother and the baby. Pregnant women who are at a higher risk for this condition will receive the medication multiple times during their pregnancy. The study will monitor how the medication is processed in the body and will check for any side effects in both the mother and the baby. This includes regular physical examinations, checking vital signs, and using ultrasound to monitor the baby’s health.
The study will also look at the presence of the medication in the baby’s blood at birth and will track the health and development of the baby for a few weeks after birth. Additionally, researchers will observe if the mother develops any antibodies against the medication, which could affect its effectiveness. The study aims to provide valuable information on the safety and effectiveness of RLYB212 for preventing complications related to Fetal and Neonatal Alloimmune Thrombocytopenia during pregnancy.



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