I really don't have a dog in this fight. Just stirring the soup and looking for fact rather than conjecture, I guess.
Anyway, this from a Pro-Choice sight:
http://prochoice.about.com/newsissues/prochoice/library/bllatetermconfusion.htm "A pregnancy is composed of three trimesters. The first trimester is from the beginning of week 1 through week 13;
the second trimester is from the beginning of week 14 through week 26; and the third trimester is from the beginning of week 27 through week 39."
...
About 12% of abortions in the United States, or
about 150,000 abortions, take place in the second trimester....
Finally, let's consider the reasons for abortion.
During the first trimester, women have abortions for various reasons mostly having to do with their own feeling that this isn't a good time to have a child.
During the second trimester, most women are still having abortions for these reasons, but some are having them because they've learned that their fetuses are abnormal, or they have concerns for their own health.As the third trimester approaches,
past the 24th week, women only have abortions because they've been given a diagnosis of severe fetal defect or, very rarely, for their own safety. Most states prohibit abortion past the 24th week, and in any case it's extremely difficult to find a provider for such a late abortion."
So, there's a little more light on the subject but not much.
It would seem to support your previous hypothesis that after the
24th week anyway. Possibly not at the 21st week, the time of the picture in question, however. They still cite "reasons mostly having to do with their own feeling that this isn't a good time to have a child" in this area.
As you say, I think it would be pretty difficult to get unbiased stats from ANY source.
Figures lie and liars figure.