Does a woman's immune system change after having a baby?

Probably not. A woman's immune system maybe altered id a certain illness or reaction in utero has happened during the pregnancy. If she contracts rubella, fifth disease or chickenpox, for example, her immune system will be augmented. If her blood type is rh negative and the blood of her rh positive fetus enters her circulation by accident, she could develop rh antibodies that might affect the baby's health.