I don't think you're understanding basic logic.
You said: "But perhaps much more important, have you considered how many more -birthed- children there would be who would die between birth and the age of five if a significant proportion of those 40 million abortions didn't occur?"
If a "significant proportion" of abortions didn't occur, then deaths between the ages of birth and five would necessarily rise (outside of a freak miracle of absolutely ZERO of those children dying between birth and five) because ALL of those people, by definition, have now made it to birth before dying.
I said (to make a point about the silliness of what you said): "Have you considered how many more -elder- adults there would be who would die over the age of 65 if a significant proportion of those X million deaths between the ages of 0-64 didn't occur?"
If a "significant proportion" of deaths between 0-64 didn't occur, then deaths from the ages of 65+ would necessarily rise (because ALL of those people, by definition, have now made it to age 65 before dying).
Don't have children that you can't provide for.