Final answer:
If a woman is Rh- and the father is Rh+, the presence of Rh+ antigens in the fetus causes the mother to produce anti-Rh antibodies, which can cross the placenta and cause hemolytic disease of the newborn.
Step-by-step explanation:
When a woman is Rh- and the father is Rh+, the child can be Rh+. In this case, the presence of Rh+ antigens in the fetus causes the mother to produce anti-Rh antibodies. These antibodies can cross the placenta and attack the fetal blood, which can lead to a condition called hemolytic disease of the newborn (HDN). HDN can cause anemia and can be potentially lethal for the baby.