Pregnancy from two parents with incompatible blood types, can it lead to complications?
The rhesus factor (the + / - part of the blood group) can cause complications with pregnancy under certain conditions and lead to the so called Rh disease:

If the mother is rhesus negative and the father, rhesus positive; then the birth of a child with Rh+ blood group (inherited from the father) can cause the mother to build antibodies against this blood group. Therefore, a second pregnancy with a child that also has Rh+ blood group can have complications if no precautions are taken at any other point.

If these specific conditions are not all met, then no complications should arise from the blood groups.