If you're RhD negative and your baby is RhD positive, and you haven't already been sensitised, you'll be offered an injection of anti-D immunoglobulin within 72 hours of giving birth. The injection will destroy any RhD positive blood cells that may have crossed over into your bloodstream during the delivery. This means your blood won't have a chance to produce antibodies and will significantly decrease the risk of your next baby having rhesus disease.