You can watch this video to understand the proper mechanisms behind the working of RhoGAM that is given as a precaution to avoid Rh sensitization and complications in the fetus that can occur if its not administered. Timeline: 0:00 - Introduction 1:05 - Rh status and blood types 3:00 - Sensitization 3:45 - Post-sensitization manifestations 4:32 - Mechanism of RhoGAM and time of administration