"Put another way, even if one believes abortion is permissible, it likely remains a comparable problem to any problem of infant mortality – but with even more lost life-years, and occurring on a much larger scale than infant mortality".

Well, it isn't comparable, because abortion prevents forced birth, and forced birth is a form of torture. As indeed is being forced to care for a child in poverty.

"Other responses to Thomson highlight various other disanalogies between pregnancy and the violinist situation: In most cases of abortion, the woman is responsible for both the child’s neediness and their intimate biological relationship with the woman – unlike the violinist case. Other responses to Thomson highlight various other disanalogies between pregnancy and the violinist situation: In most cases of abortion, the woman is responsible for both the child’s neediness and their intimate biological relationship with the woman – unlike the violinist case."

Bit of a bold statement, and likely untrue. It is impossible for a woman to know even when having unprotected sex if it will result in a pregnancy. Contraceptive technologies fail. And what about the responsibility of the father? It takes two.

"n the case of abortion, the woman is the mother of the child[6] – unlike the violinist case.[7]"

Ok, this is meaningless.

"The violinist is in an unnatural situation and being hooked up to the stranger is an unnatural position – by contrast, the fetus is exactly where she is supposed to be in her ‘natural habitat’."

Not in my womb, it isn't, motherfucker!

Quite a lot of pregnancies end early in miscarriage.