In Judaism, views on abortion draw primarily upon the legal and ethical teachings of the Hebrew Bible, the Talmud, the case-by-case decisions of responsa, and other rabbinic literature. In the modern period, moreover, Jewish thinking on abortion has responded both to liberal understandings of personal autonomy as well as much Christian opposition to abortion. Contemporarily speaking, observant Jews firmly oppose abortion after the 40th day, with health-related exceptions, and liberal Jews tend to allow greater latitude for abortion.
The Torah says little about the status or treatment of the embryo or fetus. Indeed, only one crucial Biblical law establishes a rule about the killing of an embryo or fetus. Specifically, Exodus 21:22-25 states:
When men fight, and one of them pushes a pregnant woman so that her children depart (yatsa), but no other damage (ason) ensues, the one responsible shall be fined according as the woman's husband may exact from him, the payment to be based on reckoning. But if other damage ensues, the penalty shall be life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise.
Under Jewish Biblical exegesis, abortion is not deemed murder. Instead, unintentional abortion is a form of damages subject to monetary compensation. Conversely, the killing of the mother—the other damage (ason)—is murder.
Early rabbinic Judaism
In mainstream rabbinic Judaism, the Biblical verse is one of several key texts that substantiate the later rabbinic prohibition on abortion, albeit not as murder. Owing partly to this verse, rabbinic law or halakhah sanctions abortion under some circumstances, namely for medical reason. In principle, Judaism does not regard the fetus as a full human being. While deliberately killing a day old baby is murder, according to the Mishnah, a fetus is not covered by this strict homicide rule. In reading of Biblical homicide laws, rabbinic sages argue that homicide concerns an animate human being (nefesh adam from Lev. 24:17) alone, not an embryo... because the embryo is not a person (lav nefesh hu).However the Talmud (Sanhedrin 57b) says that a fetus is included in the Noahide prohibition of bloodshed (distinct from homicide) that is learned from Genesis 9:6 that states (in a direct translation from the Hebrew); He who spills the blood of man in man shall have his blood spilt. The Talmud interprets "the blood of man in man" as to include a fetus, which is the blood of man in man. Things that are prohibited under the Noahide laws are also prohibited to Jews. The penalty of having his blood spilt, in regard to Jews, is interpreted by Maimonides as referring to a punishment by the hands of heaven, and not by the courts.
A core text in rabbinic law crystallizes the status of the fetus. The Mishna explicitly indicates that one must abort a fetus if the continuation of pregnancy might imperil the life of the woman.
If a woman is in hard travail, one cuts up the offspring in her womb and brings it forth member by member, because her life comes before the life of her foetus. But if the greater part has proceeded forth, one may not set aside one person for the sake of saving another.
According to the text this can be done until the point of yatza rubo (יָצָא רֻבּוֹ), that "the greater part has proceeded forth". This is taken to refer to the emergence of the baby during childbirth.
In Talmudic law, an embryo is not deemed a fully viable person (bar kayyama), but rather a being of "doubtful viability" (Niddah 44b). Hence, for instance, Jewish mourning rites do not apply to an unborn child. The status of the embryo is also indicated by its treatment as "an appendage of its mother" (ubar yerekh 'imo Hullin 58a) for such matters as ownership, maternal conversion and purity law. In even more evocative language, the Talmud states in a passage on priestly rules that the fetus "is considered to be mere water" until its 40th day. In another passage the Talmud speaks of a "moment of determination" and a "moment of creation" in regard to different stages of the fetus. Rashiexplains that the moment of creation is when bones and arteries begin to form and in other places he says that the "moment of creation" is at the 40th day.
Later authorities have differed as to how far one might go in defining the peril to the woman in order to justify abortion, and at what stage of gestation a fetus is considered having a soul, at which point one life cannot take precedence over another.
Medieval and pre-Modern Judaism
After the Talmudic period, Jewish views on abortion become more refined, and diverse, as rabbinic literature expanded and Jewish philosophy developed. Maimonides, notably, justified the requirement to abort a pregnancy that threatens the woman's life not because the fetus is less than a nefesh (human being), as the Talmud held, but rather through the principle of the rodef or pursuer, "pursuing her to kill her." Schiff argues that the Maimonidean view is "unprecedented" and "without doubt, this hitherto unexpressed insight had dramatic potential ramifications for the parameters of permissible abortion." Meir Abulafia and Menachem Meiri reaffirm Rashi's view.
Another reason to prohibit abortion is found in the Talmudic commentaries known as the Tosafot. The Tosafot argued that abortion is forbidden to Jews because it is forbidden to non-Jews under the Noahide laws. "A gentile is culpable for the death of a fetus, while a Jew is forbidden to cause its death but is not culpable." Here the Tosafot follows the statement in the Talmud (Sanhedrin 59a) that there is nothing that is prohibited to the Noahide that is permissible to Jews, that Jews are not permitted actions that are forbidden to gentiles, though the (theoretical) punishment for violations would apply only to gentiles. Relying on such reciprocal logic, the Tosafot also hold that, since Jews are permitted therapeutic abortions for the sake of maternal life, then Noahide law likewise allows non-Jews to undergo therapeutic abortion. Given this near parity, rabbinic law prohibits Jews from assisting gentiles with forbidden abortions, for which the gentiles would be culpable of bloodshed. Viewing Noahide law as a universalizing ethics, Sinclair states: "it is evident that the halakhah in the area of foeticide is shaped by a combination of legal doctrine and moral principle." However, the Tosafot text that applies Noahide law to forbid abortion does not go unchallenged. Another commentary in Tosafot (Niddah 44b) appears to question whether foeticide is permitted. However this is not the plain interpretation of that Tosafot.
Scholars of Talmudic and Medieval rabbinic law draw a sharp contrast between the theologies behind Jewish and Catholic opposition to abortion. After favorably reviewing Christian opposition to abortion, Immanuel Jakobovits writes inJewish Medical Ethics: "In Jewish law, the right to destroy a human fruit before birth is entirely unrelated to theological considerations. Neither the question of the entry of the soul before birth nor the claim to salvation after death have any practical bearing on the subject." Although halakhic regulations works strenuously to protect the unborn child, he says that "none of these regulations necessarily prove that the foetus enjoys human inviolability." In contrast to the neo-Platonic and Christian approach, moreover, Talmudic thought does not "make any legal distinction between formed and unformed foetuses," after the 40th day. Feldman, likewise, is emphatically comparative, saying: "... while Christianity's position on abortion has raised the moral level of western civilization in this regard and has succeeded in sensitizing humanity to a greater reverence for life, it is obviously comprised, at the same time, of theological postulates which the Jewish community can not share." Feldman also points out that Talmudic debate over whether the soul achieves immortality upon conception, or at a far later stage, has little bearing halakhic protections for the fetus because, absent a doctrine of original sin, "abortion would not interfere with the immortal rights or destiny of the foetus."
In the standard code of Jewish law, the Shulchan Aruch, therapeutic abortion is permitted; Maimonides's language, speaking of the fetus as pursuer, is included verbatim. A key commentator, R. Joshua Falk, explains that abortion does not trade off one life for another life because the embryo is "not a person" prior to birth. An ordinary abortion is a violation of civil or monetary law, not criminal law, as emphasized by R. Ezekiel Landau among others.
In a key responsum, R. Yair Bachrach is asked whether to approve an abortion for a woman with an illegitimate embryo. R. Bachrach distinguishes early stage from later stage abortions. His reasoning is based on a Talmudic commentary to the effect that Sabbath laws may be violated for a fetus, but only for a later-stage embryo. Several authorities say that Jewish law is less strict for terminating embryos before 40 days. He also concludes that the embryo may be treated as a pursuer rodef, as Maimonides as opined, though simultaneously he upholds Rashi's view of the reduced status of the fetus. Bachrach then offers a novel rationale for denying the requested abortion. He argues the abortion, like certain forms of contraception, frustrates the mitzvah of reproduction and destroys the "seed" needed to be "fruitful and multiply."
With the emergence of modern Jewish identity in the late 18th century, Jewish views on abortion have bifurcated along movement lines, especially between Orthodox Judaism and its more liberal counter-parts. By the 20th century, liberal-minded Jews were among those most active in the pro-choice movement. These reproductive rights activists included Betty Friedan, Bernard Nathanson, and Gloria Steinem (however, later in life Nathanson became a pro-lifeactivist and converted to Catholicism). In the U.S., a few politically-conservative Republican Jews also have been pro-choice. A few Jewish groups concentrate on abortion issues, both pro-life and pro-choice.
Due to the diversity within Orthodox Judaism, there are a range of halakhic opinions about abortion, though they generally prohibit abortion except in quite limited circumstances. All agree, however, that abortion is not only acceptable but mandatory to save a woman's life.
In 2001, Jewish ethicist Daniel Eisenberg summarized the typical exceptions permitted by some authorities: "Judaism recognizes psychiatric as well as physical factors in evaluating the potential threat that the fetus poses to the woman. However, the danger posed by the fetus (whether physical or emotional) must be both probable and substantial to justify abortion. The degree of mental illness which must be present to justify termination of a pregnancy is not well established and therefore criteria for permitting abortion in such instances remain controversial."
Some Orthodox law deciders (poskim) forbid abortion to prevent the birth of a severely defective fetus.
Nonetheless, on scattered occasions, rabbinic authorities have issued more lenient rulings on abortion. Notably, a recent rabbinical authority holds the minority view that a child with known Tay-Sachs disease may be aborted due to its dismal prognosis. As Eisenberg notes, "Rabbi (Eliezer) Waldenberg allows first trimester abortion of a fetus which would be born with a deformity that would cause it to suffer, and termination of a fetus with a lethal fetal defect such as Tay Sachs up to the end of the second trimester of gestation."
Among Orthodox Jews, abortion has re-emerged as a controversial topic due to the debate over stem cell research. In general, Orthodox Jewish medical ethics tend to favor medical research. Some interest has been articulated to support stem cell research and, in so doing, demonstrate Jewish law's leniency toward abortion of "pre-embryo" cells. Thus, Eisenberg emphasizes that "Rabbi Yechiel Weinberg (author of the Responsa Seridei Aish), clearly held that there is no prohibition of abortion before forty days according to Rabbi Trani's opinion since there is no 'limb' to injure prior to formation of a recognizable fetus at forty days. Rabbi Weinberg himself at first permitted abortion prior to forty days, but later reconsidered his position, not because of the prohibition on abortion, but out of different considerations" In writings on stem cell research, Rabbi Moshe Dovid Tendler has supported the use of pre-embryonic cells, whereas Rabbi J. David Bleich has opposed destruction of stem cells.
The Rabbinical Assembly Committee on Jewish Law and Standards takes the view that an abortion is justifiable if a continuation of pregnancy might cause the woman severe physical or psychological harm, or when the fetus is judged by competent medical opinion as severely defective. The fetus is a life in the process of development, and the decision to abort should never be taken lightly. Thus, the Conservative position is in line with some of the Acharonim who permit an abortion in case of acute potential emotional and psychological harm.
Before reaching her final decision, Conservative Judaism holds that the woman should consult with the biological father, other members of her family, her physician, her Rabbi and any other person who can help her in assessing the many grave legal and moral issues involved.
Reform Judaism permits abortion, not only when the woman's life is at stake, but also when a pregnancy is "a result of rape or incest; when through genetic testing, it is determined that the child to be born will have a disease that will cause death or severe disability, and the parents believe that the impending birth will be an impossible situation for them," and for several other reasons. More generally, the "Reform perspective on abortion can be described as follows: Abortion is an extremely difficult choice faced by a woman. In all circumstances, it should be her decision whether or not to terminate a pregnancy, backed up by those whom she trusts (physician, therapist, partner, etc.). This decision should not be taken lightly (abortion should never be used for birth control purposes) and can have life-long ramifications. However, any decision should be left up to the woman within whose body the fetus is growing."
The Reform Movement has acted to oppose legislation that would restrict the right of women to choose to abort a fetus, especially in situations in which the health of the woman is endangered by continued pregnancy. This pro-choice position has been linked by some Reform authorities to the value that Reform Judaism places upon autonomy—the right of individuals to act as moral agents on their own behalf. In writing against a legal ban on so-called "partial birth abortion," Rabbi David Ellenson, president of the Reform Movement's Hebrew Union College, has written, "This law as it has been enacted unquestionably diminishes the inviolable status and worth that ought to be granted women as moral agents created in the image of God."
Jews and abortion policies
In the United States, Orthodox Jews are usually affiliated with the National Pro-Life Religious Council, whereas Conservative Judaism, Reconstructionist Judaism and Reform Judaism are usually aligned with the interfaith Religious Coalition for Reproductive Choice.  Nonetheless, Orthodox organizations such as the Orthodox Union and Agudas Yisrael have occasionally partnered with pro-choice organizations when necessary to ensure that abortions will be available to women whose lives are endangered by the fetus.
As feminists or health professionals, Jews have been among those most active on reproductive rights advocacy in the U.S. Generally, Jews have been less involved with the pro-life movement.
In July 2012, Tablet Magazine, an online Jewish publication, quoted the Public Religion Research Institute’s 2012 Jewish Values Report: "American Jews are overwhelmingly in favor of abortion in all (49%) or most (44%) cases. There is little denominational or demographic variation on this level of overall support." The author went on to summarize:
"That’s 93%, folks. The report goes to explain that while opinions are more varied by political affiliation among Jews, over 75% of Jewish Republicans believe that abortion should be legal in all or most cases. From the data, it seems that Wasserman Schultz isn’t saying anything that isn’t reflective of the vast majority of Jewish opinion. In fact, it seems that access to abortion is the issue upon which the most Jews agree." 
In Israel, abortion is allowed at the request of a termination committee in the cases of if the woman is unmarried, age (if the woman is under the age of 17 - the legal marriage age in Israel - or over the age 40), the pregnancy was conceived under illegal circumstances (rape, statutory rape, etc.) or an incestuous relationship, birth defects, risk of health to the mother, and life of the mother. According to the Israel Central Bureau of Statistics report from 2004, in 2003 most abortion requests were granted, with 19,500 legal abortions performed and 200 requests for abortion denied. Reasons for termination went as follows: the woman was unmarried (42%), because of illegal circumstances (11%), health risks to the woman (about 20%), age of the woman (11%) and fetal birth defects (about 17%).