In the Lord's Prayer it says, "thy kingdom come, thy will be done, on Earth as it is in Heaven." The implication is that there is this perfect place that we can only imagine, where everything is good because that is the Lord's will. The prayer is that this same good will should reform/refine Earth in the image of heaven.
So now ask yourself if you believe there is sex and abortion in heaven? First, the question is whether sex and reproduction are really something truly perfect or if they are a necessity for perpetuating life in this imperfect world where biological organisms die.
The next question is that if death is an inevitability of the flesh, and thus sex and reproduction are a necessity for the perpetuation of life, what is the best way to handle that? Should we allow death to be determined by nature, or should we take the power of death into our own hands as imperfect humans with flawed motives and interests?
Another question is to ask what the relationship is between sexual intercourse, reproduction, and happiness. Can people be happy without intercourse except for the purpose of reproduction? Maybe they can and they just don't know it because sex is marketed to them in so many ways. "Sex sells," the proverb goes, so we are constantly being marketed sex to stimulate sales for people trying to make money off us.
So the issue isn't really whether dead children/babies/fetuses go to heaven, but how to follow through on the Lord's Prayer and attempt to honor and thus facilitate "thy kingdom come, thy will be done, on Earth as it is in heaven."