They aren’t. Get informed.
Show me in the platform, where they offer any obstacle or opposition, to any abortion, at any level, at any stage, they absolutely are pro-abortion.
Libertarian Party Platform
1.4 Abortion
Recognizing that abortion is a sensitive issue and that people can hold good-faith views on all sides, we believe that government should be kept out of the matter, leaving the question to each person for their conscientious consideration.