From my understanding (as a biology professor, not a medical doctor), this should not pose a problem. Problems can arise when the mother is a negative blood type.
Here's why:
Negative blood types are lacking a certain protein that positive blood types have. If a woman has a negative blood type (no protein) and she has a child with a positive blood type (has protein), her immune system may recognize that protein as a threat, causing complications in pregnancy.
However, for a woman who has a positive blood type, her immune system has already learned to recognize the protein as non-harmful, so there should not be difficulties resulting from blood type during pregnancy.
Here's why:
Negative blood types are lacking a certain protein that positive blood types have. If a woman has a negative blood type (no protein) and she has a child with a positive blood type (has protein), her immune system may recognize that protein as a threat, causing complications in pregnancy.
However, for a woman who has a positive blood type, her immune system has already learned to recognize the protein as non-harmful, so there should not be difficulties resulting from blood type during pregnancy.