with all the rights inherent to you and I, then it's reasonable to draw the line at viability. If you birth a baby prior to 24 weeks from the last menstrual period, then that baby has no chance of survival, since it can't produce pulmonary surfactant. Now, I have seen to D&Es around that point and I've made the mistake of looking at the back table. I prefer not to have nightmares, so I hope never to see that again.

Exceptions after that point probably ought to center of fetal viability, like genetic conditions incompatible with life, or risks to the mother's life. There's obviously a point at which carrying a baby is no longer just a woman's choice but you basically have a cooked bun in the oven. I draw that line at viability: if you can extract that baby from the uterus and keep that baby alive long enough to reach adulthood, women should not be allowed to terminate that pregnancy without an extenuating circumstance.