‘The Fetus Is A Limb Of It’s Mother’
The Gemara (Temurah 25b) cites a Tannaitic dispute as to whether a fetus is viewed as a limb of its mother (“ubbar yerech immo”), or is considered an independent entity (“ubbar lav yerech immo”).
Rava on our daf states that if a pregnant woman converts to Judaism, the immersion that she undergoes for her conversion is valid for her fetus as well, and thus when her child is born it need not undergo immersion to become Jewish.
Initially, the Gemara assumes that this halacha is based on the principle that the mother’s conversion transforms her fetus into a Jew because the fetus is viewed as part of her body and that is why he need not undergo tevilah after birth.
Subsequently, the Gemara suggests that Rava’s halacha conforms even with the view that holds “ubbar lav yerech immo,” namely, that a fetus is not regarded as a limb of its mother but is a separate entity. Rava is saying that when the mother immerses in the mikveh, her fetus also undergoes an immersion, and therefore there is no need to perform another immersion after birth. [The Gemara explains that even though the mother’s body does not allow the mikveh water to come in contact with the fetus, the womb is not considered an interposition since “haynu revisei” – the fetus is in its natural place of growth.] Since the fetus is inseparable from its mother as it grows, it is as if the fetus is immersed, even though it is considered a separate entity.
Immersion Without Circumcision?
Ritva (Yevamos 47b) is of the opinion that when this pregnant convert gives birth to a boy, he is a Jew at birth, before undergoing circumcision, even though the conversion process for male converts entails both tevilah and milah (immersion and circumcision). Since at the time of his immersion he was in a state in which he was unfit to undergo milah (as he was a fetus), he assumes the status of a female ger whose conversion is effected with tevilah alone.
Ramban disagrees and is of the opinion that the baby boy’s conversion is not complete until he undergoes milah.
Rashba (Yevamos 47b) is of the view that our Gemara refers to a baby girl as well – she needs no immersion, but a boy needs both circumcision and immersion.
The Mishna (Bechoros 46a) states that if a woman converts while she is pregnant with her bechor (firstborn), he is subject to the mitzvah of pidyon haben – the redemption of the firstborn – since he was born to a Jewish mother. [However, if a firstborn non-Jewish boy undergoes conversion (together with his mother) after his birth, he is exempt from pidyon haben, since he was not born to a Jewish mother and was therefore not Jewish at birth.]
The Keren Orah (Yevamos 78a) notes that this Mishna seems to support Ritva’s position that the fetus becomes a full-fledged convert at the time of its mother’s conversion. According to Ramban’s opinion, it is difficult to understand why he is subject to the mitzvah of pidyon haben since the baby boy must complete his conversion after birth by undergoing circumcision (milah). He should be granted the same exemption as a firstborn non-Jew who converts to Judaism after birth.
The Point of Conversion
In answer, the Keren Orah explains that the Tanna of the Mishnah in Bechoros is a proponent of the position “ubbar yerech immo” – that the fetus is considered a limb of its mother. Ramban agrees with Ritva that according to the position that a fetus is its mother’s limb, the baby boy born to a pregnant convert need not undergo milah to complete his conversion. (Rather, his milah is a separate requirement, a mitzvah incumbent on all Jews.) According to this view, when the mother undergoes conversion and becomes Jewish, her fetus automatically becomes Jewish by virtue of the fact that it is part of its mother’s body, not because it personally underwent a conversion process. Ramban requires the baby boy to complete his conversion after birth (through milah) only according to the position that “ubbar lav yerech immo” – the fetus is a separate entity.