A Study to Evaluate the Safety, Efficacy, Pharmacokinetics and Pharmacodynamics of M281 Administered to Pregnant Women at High Risk for Early Onset Severe Hemolytic Disease of the Fetus and Newborn (HDFN)

The purpose of this study is to evaluate the safety in mother and neonate/infant of M281 administered to pregnant women who are at high risk for Early Onset Severe Hemolytic Disease of the Fetus and Newborn (EOS-HDFN). The effectiveness of the investigational drug M281 will be measured by looking at the percentage of participants with live birth at or after gestational age (GA) 32 weeks and without a need for an intrauterine transfusion (IUT) throughout their entire pregnancy.