http://www.buddhistethics.org/5/barnh981.html
Here are a few excerpts.
Now, I will say up front I have rarely ventured into the Right and Wrong Forum, know very little about Buddhism, and have ambivalent attitudes towards abortion.It is quite clear from a variety of sources that abortion has been severely disapproved of in the Buddhist tradition. It is also equally clear that abortion has been tolerated in Buddhist Japan and accommodated under exceptional circumstances by some modern Buddhists in the UṢ. (1) Those sources most often cited that prohibit abortion are Therav�din and ancient. By contrast, Japanese Buddhism as well as the traditions out of which a more lenient approach emerges are more recent and Mah�y�na traditions. Superficially, the situation seems not unlike that of Roman Catholicism, where abortion, though disapproved of in the strongest terms by Church authorities drawing on the canonical tradition, is nonetheless practiced by a large number of devout Catholics and defended by at least a few, sometimes renegade, theologians and philosophers, as acceptable in some circumstances. Therefore, if it makes sense to speak of a possible Catholic defense of abortion, then it makes equally good sense to speak of a Buddhist defense of abortion, a defense made in full knowledge that one is swimming against the tide of conventional interpretation but still within the tradition. In other words, I am not so much concerned to show that Buddhism has, does, or will support the choice to abort or one's right to make such a choice as I am to show that such a choice can be made in a manner consistent with Buddhist principles.
. . . . .
One of the strongest antiabortion cases from a Buddhist perspective emerges in Damien Keown's wonderfully thorough and insightful analysis of Buddhism's bioethical ramifications in the book Buddhism and Bioethics. (2) Keown argues that the preponderance of the Buddhist traditon is overwhelmingly antiabortionist. In support, he develops two lines of argument. The first relies on the nearly uniform rejection of abortion, especially in ancient Therav�da texts, what Keown regards as the core of the tradition. Here I believe he is on fairly firm ground although I am uncertain regarding his preference for what he calls "Buddhist fundamentalism" and his concomitant emphasis on "scriptural authority." (3) The second line of argument concerns his interpretation of these sources and their connection to the basic tenets of Buddhism regarding the nature of personal identity and the skandhas, karma and rebirth, life and death.
Questions for debate:
1) Does the tradition of anti-abortionism in Buddhism bolster the morally based arguments made by Christians against abortion?
2) Does this tradition put to lie the contention that anti-abortion attitudes stem predominantly from Christian Conservatism?