It is a concern because people have a right to make a living. It is important because people have a right to food, clothing and shelter. That's why abortion is the key issue. Deny that a person has the right to live, and you undercut the importance of every other issue. It is impossible to coherently speak up about any issue impacting human life if you are allowing the life itself to become a disposable item.
Abortion is more than abortion.
We speak more often of the pre-born precisely because we are trying to UNDO the unfair distinction made between them and the born. The pre-born have equal rights with the born, and we demand that those rights be respected in the same way. To accuse pro-lifers of not having concern for the born is as unfair as accusing prison chaplains of not having concern for those who are free. Having a universal concern for human rights never excludes a person from having a specific focus on one group of people in need. The pre-born, furthermore, are most in need.