I'm thinking that somewhere around 14 weeks for elective abortions with no specific medical reason to abort. That gives a woman 3 1/2 months to decide what to do and is well before viability and the possibility of cognitive function.

I'd allow up to 26 weeks for documentable medical reasons such as the mother's life being threatened or the fetus having severe medical issues.

Beyond 26 weeks, INDUCE LABOR and give the fetus a fighting chance. A fetus has a fighting chance at some point beyond 24 weeks. Babies born earlier don't typically survive, although a very rare one does. They usually face a lifetime of severe medical issues prior to 28 weeks gestation, but a few have survived as early as 21 weeks.

In most cases where a woman's health is at risk, if an infant has passed the 24 week mark, doctors will attempt to get as far as possible, with the woman hospitalized, to increase the chances of survival of the fetus while being at the ready to save the life of the mother however necessary.

We went through all of that last year with our eldest daughter. She was critically ill with a life-threatening intestinal puncture (from Crohn's complications) and a raging peritoneal infection which made itself known when she was 21 weeks pregnant. She was hospitalized in Brigham & Women's for the rest of her pregnancy while on heavy antibiotics to resolve the infection and a feeding tube because she couldn't eat.  She lost so much weight that she was nearly skeletal, but she pulled through it.  It was THE worst experience of her young life and ours too. 

Doctors were able to get our granddaughter, Evelyn, through to 32 weeks gestation before it became necessary to induce labor immediately to save both of them as J had been sporadically bleeding for a couple of weeks, but it became steady and a deadly hemorrhage became very likely. Evelyn was born weighing barely 4 lbs but she thrived and has grown into an adorable little cherub who is now almost 14 months old.

Our daughter had to have resection surgery to remove her severely damaged ileum section of her intestines and then to resection the large and small intestines back together and then have a feeding tube for another 2 months until it was healed enough to eat food.

So, I'm very much aware of the need for legal abortion to save the life of the mother. NO ONE aborts a fetus so far along without a REALLY GOOD REASON and NO doctor would do it anyway. Beyond the first trimester, abortion is NOT a simple procedure and it requires a doctor.