Two points should be made. First, if the unborn child is an intrinsically valuable human being, then abortion in the case of a terminal diagnosis is wrong. For we may not intentionally kill someone on the grounds that she will soon die as a result of disease or abnormality, or because her abbreviated existence will cause another person emotional distress. In his new book The Ethics of Abortion: Women's Rights, Human Life, and the Question of Justice, philosopher Christopher Kaczor explains:
[I]t seems clear that the expectant lifespan of a person does not make a difference in whether or not a person may be killed. The fact that a person at the end of life may have only a short time to live does not imply the permissibility of killing that person. If someone is scheduled to be executed, that fact does not authorize private persons to kill the death row inmate earlier. Indeed, the prospective lifespan of a human person varies a great deal depending upon [various] factors ... The prospective lifespan of a human being is irrelevant to the question of the permissibility of killing. So, if the human being in utero is a person, then killing is impermissible even if the human being will die of other causes in a few weeks.Extreme disability or deformity does not justify killing the unborn any more than it justifies killing those (disabled or deformed people) who are already born. Rather, to justify abortion, one would have to demonstrate that the unborn human being does not merit the kind of basic regard each of us (you, me, a terminally-ill teenager, etc.) merits -- the kind of regard that precludes intentional killing. The fact of a terminal diagnosis is simply not ethically relevant.
Second, choosing abortion when a child has a fatal defect probably does not best serve the pregnant woman's emotional and psychological health (as those advocating for abortion assume). She seems better served when her unborn child is treated as a real patient deserving care, and that is what the option of perinatal hospice and palliative care is all about. From perinatalhospice.org:
In an era of evidence-based medicine, it's important to note that there is no research to support the presumption that terminating the pregnancy is easier on the mother psychologically. In fact, research to date suggests the opposite. Research suggests that women who terminate for fetal anomalies experience grief as intense as that of parents experiencing a spontaneous death of a baby (Zeanah 1993) and that aborting a baby with birth defects can be a "traumatic event ... which entails the risk of severe and complicated grieving." (Kersting 2004) One long-term study found that "a substantial number ... showed pathological scores for post-traumatic stress." (Korenromp et al, 2005) And a recent followup study found that 14 months after the termination, nearly 17 percent of women were diagnosed with a psychiatric disorder such as post-traumatic stress, anxiety or depression. (Kersting 2009) Termination is not a shortcut through grief. In contrast, parental responses to perinatal hospice are "overwhelmingly positive" (Calhoun & Hoeldtke 2000), and parents report being emotionally and spiritually prepared for their infant's death and feeling "a sense of gratitude and peace surrounding the brief life of their child" (Sumner 2001).Perinatal hospice is a wonderful alternative that is ethical, compassionate and healthy for everyone involved. To learn more, see perinatalhospice.org and benotafraid.net, as well as Amy Kuebelbeck's books Waiting with Gabriel: A Story of Cherishing a Baby's Brief Life and A Gift of Time: Continuing Your Pregnancy When Your Baby's Life Is Expected to Be Brief.