Blood groups

Ca
My midwife says my blood group is O rhesus negative.
Does anyone else know which blood group they are? Is anyone else rhesus negative?
If my husband is rhesus positive and we have a rhesus positive baby, my body could make antibodies to attack positive blood cells unless I have an injection to prevent this.
I haven't had any injections yet, but I am only 16 weeks pregnant. Does anyone know what the procedures are?