When my son was born on a Friday and I contacted a mohel to schedule the bris for the following Saturday, I was surprised to be asked whether the baby had been delivered by Caesarean section. If boys are delivered traditionally, I learned, they must be circumcised on their eighth day of life; but if they are delivered by C-section, the ritual can be postponed if the eighth day falls on Shabbat. I didn’t ask the mohel for the halakhic reasoning behind this distinction—as a new parent I had enough things to think about—but I finally learned it from reading the Talmud this week.Caesarean section in antiquity was usually done either in cases when the mother was already dead or when both mother and baby could be expected to die without intervention. This particular intervention would have a chance to save the baby, but the survival of the mother, although it (remarkably) was not unheard of, would have been unusual. For some data on pre-modern Caesarean section see Samuel Lurie's article The changing motives of cesarean section: from the ancient world to the twenty-first century.
In Shabbat 135a, Rabbi Asi explains that the distinction has to do with the ritual purity status of the mother. Vaginal delivery renders the mother impure, tamei, for seven days, and it is only at the expiration of this term that circumcision takes place, as we learn from Leviticus: “If a woman bears seed and gives birth to a male, she shall be impure seven days, and on the eighth day the flesh of his foreskin shall be circumcised.” The rabbis drew the corollary that, if a woman is not impure because she delivered by C-section, her son does not need to be circumcised on the eighth day. And since it is preferable not to perform a circumcision on Shabbat unless absolutely necessary, the circumcision or milah can be postponed until the ninth day in such cases. Of course, in Talmudic times Caesarean section would have been a very rare and dangerous operation, performed without anesthetic using unsterilized tools. The rabbis could hardly have imagined that in our day almost a third of births would happen this way.
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As I have remarked before, it is difficult to imagine the brutality of the world in which the ancients lived.
Earlier Daf Yomi columns are noted here and links.