Im neg and have had anti D with most of my preggys. However I had a miscarridage and D&C with no anti D afterwards (its an illegal blood product here for some stupid reason) so the hospital couldnt give me anti D. This baby we bought Anti D from HK rare blood org and they said- best results were to have a shot at 30 weeks and after birth. doubling up on shots in 3rd tri showed no added safety.
WE had alot of trouble getting my Anti D shot after baby for legal reasons, but hospitals here were very interested as here RH Neg mothers have alot of trouble getting to term or producing healthy babies. So hopefully our information (it was weird teaching the drs about something) have saved some families heartache.
But it is stil a personaly thing, some mothers choose to take the risk and not get the shots. I have always had my shots (when I can)