“A Jew is governed by such reverence for life that he trembles lest he tamper unmindfully with the greatest of all divine gifts, the bestowal or withholding of which is the prerogative of G-d alone. Although he be master over all within the world, there remain areas where man must fear to tread, acknowledging the limits of his sovereignty and the limitations of his understanding. In the unborn child lies the mystery and enigma of existence. Confronted by the miracle of life itself, man can only draw back in silence before the wonder of the Lord.”
(Source: Contemporary Halakhic Problems, Volume 1. KTAV Publishing House, Inc. Yeshiva University Press: New York and Hoboken, copyright 1977, p. 370.)
"No authority permits an abortion which is non-therapeutic in nature. There are early rabbinic authorities who expressly declare that ritual laws such as Shabbat observance and fasting on Yom Kippur are suspended in order to preserve the life of the fetus. Suspension of such significant religious observances is clearly incompatible with indiscriminate license to destroy fetal life."
"As has been shown earlier, Judaism teaches that man does not enjoy unrestricted proprietary rights with regard to his own body, much less so with regard to the body of an unborn child. Furthermore, the fetus is not merely an appendage to the mother, but is a being in its own right. The Gemara concludes that the embryo is endowed with a soul a the moment of conception."
(Source: Rabbi J. David Bleich. Judaism and Healing: Halakhic Perspectives. KTAV Publishing House Inc. 1981, p. 97.)