The following letter was written to a doctor who asked the Rebbe about various medical issues in halacha. After detailing his opinion on the topics of Observant Jews being practicing physicians, the problems of "birth control" and "family planning," the Rebbe went on to discuss the issue of abortion. The Rebbe was candid in his opinion,
“The destruction of a fetus is strictly prohibited except, as mentioned, in extraordinary cases.” This law is just as applicable for Jews as is is for non-Jews as the Rebbe went on to say, “ you surely know that Jewish Law makes it incumbent upon Jews to use their influence with non-Jews to help promote the so-called Seven Laws that have been given to the children of Noah, with all their ramifications. These laws include also the prohibition of abortion.”
The Rebbe went on to make another strong point based off of the Gemara which states that Moshiach will only come after the birth of all the children who have to be born,
“Thus it is clear that when even a single woman aborts the birth of a child, it is not just her affair or her own problem, but it affects the Geulah of all our Jewish people and with it the Geulah of the whole world.”
In the Rebbe’s words:
The beginning of the letter:
The continuation of the letter, getting to the crux of the issue:
Everyone should realize that there is a Creator and Master of the world Who has prescribed a definite order by which the human race should live. The destruction of a fetus is strictly prohibited except, as mentioned, in extraordinary cases.
There is really no difference in this matter between Jewish or non-Jewish patients. First of all, you surely know that Jewish Law makes it incumbent upon Jews to use their influence with non-Jews to help promote the so-called Seven Laws that have been given to the children of Noah, with all their ramifications. These laws include also the prohibition of abortion. Indeed, for some reason, the Torah declared that destruction of a fetus by a non-Jew is even more serious than by a Jew not that abortion can be treated lightly by Jews, as outlined above.
It is well known that I do not, nor is it one of my functions, to pasken shaalos, especially as there is the Union of Orthodox Rabbis and similar Rabbinic bodies who have come out clearly and emphatically against family planning and the like. I have gone out of my way to express my views on the matter in this letter only because abortion has become now not only widely acceptable but, on the contrary, it is claimed to be a thing of justice, women's independence, etc. etc., although it makes no sense to say that a woman should have a right to kill an unborn child or even a fetus in order to assert her independence. Nevertheless, so great is the confusion and darkness of the present day and age, that even some persons of higher education and supposedly knowledgeable in the fields of ethics and philosophy and the like, have also come out in support of this evil.
Finally, I would like to make reference to a saying of our Sages which, at first glance seems incomprehensible, but it is nevertheless part of our Torah, Toras Chaim, our true guide in life. This Talmudic saying is to the effect that the true and complete Geulah will come only after the birth of all the children who have to be born. Thus it is clear that when even a single woman aborts the birth of a child, it is not just her affair or her own problem, but it affects the Geulah of all our Jewish people and with it the Geulah of the whole world.
In light of the above, there can be no doubt that it is not only proper and right, but also a direct obligation on the part of every Jew, to do whatever is possible in this area, as well as in all matters of Torah and mitzvos to the best of one's ability and influence.
With blessing,
The Letter and the Spirirt, Vol. 5, PP 116
The Halacha varies in context of levels of danger to the mother and stage of the pregnancy.
Therefore, it is imperative to consult a Rov in all cases, whether is seems to be a case where one should be maikel or machmir.