There’s been a recent wave of blog posts by people who had late term abortions because the baby was dying or would die soon after the birth. (See Andrew Sullivan, Hilzoy and others)
This comes after years of assertion from pro-life forces that most late term abortions are not to protect the life of the mother and do not involve such “mercy killing” scenarios.
Obviously both sides can offer examples — but which are most representative of the majority of cases? Amazingly, given the prominence of the issue, the evidence is murky.
Pro-life activist Jill Stanek points to two pieces of evidence:

Kansas City Star, August 26, 1991, quoting Peggy Jarman of the Pro-Choice Action League: “About three-fourths of [George] Tiller’s late-term patients, Jarman said, are teen-agers who have denied to themselves or their families that they were pregnant until it was too late to hide it.”

And, she quoted Fox News on June 13, 2007 who interviewed Paul McHugh, a psychiatrist hired by the state Attorney General when he was prosecuting George Tiller for violating Kansas law. This prosecution witness said:

“I didn’t think that those records supported the idea that these women were likely to suffer a substantial and irreversible impairment, which was required by law here in KS for their abortion since they were late-term abortions….
They highlighted certain kinds of things, which out of context were hard, of course, to appreciate, but were sometimes of a most trivial sort from saying that, “I won’t be able to go to concerts,” or “I won’t be able to take part in sports,” to more serious ones such as, “I don’t want to give my child up for adoption.”

But a jury considering the evidence actually found Tiller not guilty.
On the other hand, a pro-choice member of the Kansas City Star editorial board wrote:

“The overwhelming majority of the 250 to 300 women a year who sought late-term abortions from Tiller had planned their pregnancies. They came to him heartbroken and afraid, carrying fetuses with malfunctioning kidneys, missing organs and syndromes certain to cause death in the womb or soon after birth. A much smaller number of late-term patients were rape and incest victims, sometimes very young girls. Some were directed to Tiller by prosecutors. “

But she offers no source or proof for these assertions.
The only systematic study I’ve been able to find was one done by the Guttmacher Institute — in 1988. That study was flawed because it looked at abortions past 16 weeks and it’s likely that the reasons for an abortion at 16 weeks would be different from that at 26 weeks. Even so, the reasons listed there didn’t particularly fit with what either side was saying. (The top two reasons for having an abortion late were, “Woman didn’t recognize she was pregnant or misjudged gestation” and “Woman found it hard to make arrangements for abortion.”)
So we have a newspaper quote from 1991. A study from 1988. Testimony of a prosecution witness in a case where the prosecution lost. An unsubstantiated assertion from a pro-choice writer.
Have I missed some evidence? If so, please post it to the comment thread and I’ll update this post.
Perhaps privacy concerns have made valid studies difficult. But I can’t help but wonder whether the controversial nature has literally scared away neutral scholars.