text: It will determine what types of blood types the baby may have.  But, apparently there can't be any adverse affects.\n\nIf a father's Rh factor genes are + +, and the mother's are + +, the baby will have one + from the father and one + gene from the mother. The baby will be + + Rh positive. (this is the case for A+ and AB+ parents)\n\nProblems with the Rh factor occur when the mother's Rh factor is negative and the baby's is positive. Sometimes, an incompatibility may occur when the mother is blood type O and the baby is either A or B.\n\nSee the source for further information, or ask your doctor because i'm not in the medical profession.