my doc said 28 weeks, and that is when they gave it to me, and also at birth. That father of my baby is not in my life anymore, and I don't know his blood type, so he told me to have it it done just in case (I am Rh-) and that it wouldn't hurt the baby,
My doc. told me they routinely give rhogam at 26 weeks and then at delivery if the baby is Rh+.