Why do Pro-Lifers tend to be from the Christian Right?

It's because when you have one value you often have other values that go with it, and the values that go along with being pro-life tend to line up with being a Christian Republican. For example, putting intrinsic value on life is a Christian value, so Christians tend to be pro-life. People who are pro-free sex are often pro-abortion because you can't have that much sex and not wind up pregnant eventually, so they tend not to be Christians. Republicans tend not to value avoiding punishment for actions, so they don't see that the mother has a "right" to abort her child.