It isn't directly. But both abortion and homosexual "pride" are symptoms of the same evil, the idea that human beings can establish their own moral order based on their own understanding of how things work. We're eating of the same fruit of which Adam and Eve ate, and it's bearing the same destructive fruit. Abortion and homosexuality are two results of that fruit.
Shalom.
This idea is the only thing that distinguishes humans from lower beasts.