If the fetus is an animal then there is no issue. If its a child then its murder, which has no place in any society I would argue. The crux of this question is a religious one. According to the bible life starts when there is blood, which is something like 8 days (don’t quote me idk) into the baby’s life. If you reject blood as the symbol of life then idk man. Point is whether a libertarian can or cannot support abortion depends on where he draws the line on when the baby has the same right to life as the mother.