Aborting a gay baby would be regarded as a hate crime by some, and a woman's inviolable “right” by others. The mushy middle with vague moral underpinnings would abort them with abandon, because they'd find it embarrassing or an affront to their sense of vanity, despite the appearance of going along with the whole tolerance thing.
This would give rise to a gay pro-life movement, as improbable as that sounds.
Christian pro-lifers would be extremely resistant to accepting abortion under practically any circumstance short of a threat to the life of the mother, and many wouldn't advocate it even then. They'd put it into the hands of God and leave it at that.
It would be bizarre!