Selected Reform Responsa
Tosafot in Hulin 33a that a Jew is not permitted(/a shari) to destroy a fetus, although such an act is not to be considered murder. Uziel says that, of course, one may not destroy it. One may not destroy anything without purpose. But if there is a worthwhile purpose, it may be done. The specific case before him concerned a woman who was threatened with permanent deafness if she went through with the pregnancy. Uziel decides that since the fetus is not an independent nefesh but is only part of the mother, there is'no sin in destroying it for her sake
In the case which you are discussing, I would, therefore, say that since there is strong preponderance of medical opinion that the child will be born im erfect physically and even mentally, then for the mother’s sake(i. e., her mental anguish now and in the future) she may sacrifice this part of herself This decision thus follows the opinion of Jacob Emden and Ben Zion Uziel against the earlier opinion of Yair Chaim Bachrach.