http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5609a1.htm

Before I launch into this terribly informative but lengthy post, let me clarify: you weren't terribly far off the mark. It's just that I have this unreasonably hostile knee-jerk reaction to those "all" and "none" statements. They hit a button, get me seeing red. You'd have done better with "most", as the data below will illustrate.

Anyway, to summarize the 2004 CDC report: 839 thousand reported legal abortions in 2004, which is down 41% from its peak in 1990. 60.5% occurred at 8 or fewer weeks gestation, another 32.4% at 9 to 15 weeks. Another 3.7% occurred at 16-20 weeks, and only 1.3% occurred at 21+ weeks. 34.5% were given to minors (females under age 18 years). No statistics are given for reason for abortion, but CDC also records 4.1 million births in 2004. I've no figures on miscarriage for 2004, but previous years' data suggest that about 17% of pregnancies end in miscarriage. Taking all that into consideration, abortions were provided in about 14% of pregnancies in 2004.

http://www.cdc.gov/nchs/data/hestat/prelimbirth04_tables.pdf#02

As a comparison, there is about a 3-4% chance in any given pregnancy of the fetus exhibiting some birth defect. Some of those terminate spontaneously as a result of the defect, some of those continue to term either because the parents are unaware of the defect or make the conscious choice to have the baby despite the defect, some are terminated in abortion. Defects range from such relatively common and reparable conditions as cleft palate to rare and fatal conditions such as anencephaly. I don't have the statistics on the breakdown but as one example, based on a comparison of prevalence rates with actual birth rates, roughly a third of pregnancies identified with Down's syndrome are terminated.

(Incidentally, CDC also showed 140 thousand live births to minors, so [excluding miscarriages] roughly 2/3 of pregnant minors receive abortions while 1/3 complete the pregnancy and have a baby.)

Let's evaluate this in terms of your claim: "Nearly all abortions performed are personal choices because the girl just didn't want a baby." Well, a little over a third of abortions are for minors. I've heard that in some states the minor can seek an abortion without parental consent, so certainly there's personal choice there. But as for the rest - hard to decipher personal choice there: sometimes the parents are responding to the girl's choice, sometimes the parents are imposing their own decision - a 13-year old (there were some of those) may not get a choice when Doc says it isn't safe for her to take a baby to term.

As for the other two-thirds - hard to guesstimate on the data, but most of the sites I'm reviewing claim that about 7% of abortions are for medical necessity - momma's in trouble.

Adding in the "medical necessity" abortions in which the future bambino would otherwise face a tortured existence and those involving minors who are really too young to be taking that chance (therefore putting aside the entirely academic debate over whether it's the female's choice or her parents'), I'd have to say that roughly 15-16% are more necessity than choice.

Still, since we're talking about pro-choice advocates, rather than women who seek abortions (from your statement, "You're operating under the politically correct assumption that pro-choicers are pro-choicers and not pro-abortioners."), I'd have to say my core statement stands:

"More common are those who see abortion as a better alternative than forcing existence on some child who will then live a short and miserable life under the curse of some terrible birth defect. More common are those who remember the vast disparities in law and application of law from state to state before Roe-v-Wade, who believe that law should be based on reason and who, having studied the science, see no logical reason to deny the idiots (and the occasional bright soul who suffers one brief moment of idiocy) the right to remove a bit of mindless flesh that has not yet become a baby."