I wonder if there have been studies done of the mental health of women who were "forced" to carry their babies to term and then gave them up for adoption? If not, this could be a major contribution.
I would assume that any woman with an unwanted pregnancy is stressed, regardless of what decisions she makes: abort, keep, place for adoption. A better study might involve women who aborted and later bore children that they wanted, women who aborted and later bore children that they gave up for adoption. Even then, it may be only a rough comparison, since a woman's personal circumstances would be different with each pregnancy.