There can be pregnancy problems if the blood group of baby has different blood Rh factor than mother e.g. You have blood group O- and if your fetus has O+ or any other with positive Rh then first baby can survive and second one can not. For second baby you have to use an injection after the delivery of first baby. What ever may be the blood group of your baby, it will not harm first baby.
I Am O -ve And My Husband Is O +ve Blood Group, Will There Be Any Pregnancy Problems, What Can Be Done If So?
The name of the injection is called Rhogam...I had to take it when I was pregnant and after the delivery of both my children.