The reasons against it is usually religious and religion and state are apart. Medically there are no reasons not to since the embryo/fetus is not aware, feel no pain, can not live by itself etc. They found that the trauma for a woman to have a unwanted child would be too big and that her mental health was improved when abortion was an option. Legally and medically it's not a baby or child being aborted.The US Supreme Court found that the right to privacy also included the right to intimate privacy and in this case her body - her choice. So according to them it's in the Constitution.