Tsvi Pesach Frank(Jerusalem , 1964), another question is raised, namely, whether the embryo of a woman being converted may eventually be heir to the property of the mother.
But our chief concern here is not levirate marriage nor inheritance; it is simply whether the child will be born Jewish . As to that question, another principle is involved, one that remains undecided in the literature, namely, whether an embryo is to be considered as merely part of the mother’s body(ubar yerekh imo) or whether it is an independent personality(cf., the discussion in Tosfot to Sanhedrin 80b., s.v.,"Ubar"). The answer to this debated question touches many facets of the law. It applies, for example, to animals. If a pregnant animal is terefah, unfit for the altar or for food, is the unborn calf made unfit as part of the mother’s body, or not?(Hulin 58a) Or, for example, a priestess is not forbidden to go into a cemetery, but there is considerable opinion that a pregnant priestess may not go into the cemetery on the chance that her unborn baby may be a male; which, of course, would imply that the embryo in that case is considered to be an independent personality (see the summary of the discussion in Kol Bo Al Avelut by Greenwald, p. 76, note 27). This disputed basic question also affects the problem of abortion. If the embryo is actually an independent personality, then abortion would be murder; but if the general principle is upheld that it is merely part of the mother's body, then to save the mother there is no more crime in removing this part of the body than operating on a leg or an arm.
The basic question of whether or not the embryo is merely part of the mother’s body would apply specifically to the question asked about the unborn child of a woman being converted. If it is merely part of the mother’s body, then with her conversion, all of her including the embryo, is converted. In fact, to some extent this is apparently the fact, because the generally accepted law is that while a man being converted required both circumcision and the
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