Potter's Syndrome babies - Type I occurs in 1 in 40,000 infants. Differences in opinion put Type II as 1 in 1,500-10,000. (
http://www.potterssyndrome.org/pottersfaqs.html)
Ectopic pregnancies - about 1% of all pregnancies; of this 1%, 98% are in the fallopian tubes. Left untreated, 50% will resolve themselves (natural abortion) (
http://en.wikipedia.org/wiki/Ectopic_pregnancy)
The 13-year old who is raped and becomes pregnant? Actually, it's 10-years old (
http://www.kidk.com/news/18749314.html). I can't find statistics on how often this occurs; for the sake of argument, I'd put it down as about 1% as well.
Obviously, these arguments are the exception rather than the norm.
So, when it comes to the abortion, the Bible recognizes that the fetus is a living human being. End of discussion.
When it comes to the law, most proposed anti-abortion laws include a clause regarding the health of the mother; yet, the pro-abortion crowd does their best to shoot these down, because it's not the health of the mother they're actually concerned about; it's the free availability of abortions.
Do we make laws for the whole of society? Or do we make them based on the "exception to the norm"? Or do we compromise, and make them with clauses that recognize the exception to the norm?