“From one month old and above” – we learned there: A baby who was born in the eighth month, one may not desecrate Shabbat for his sake, one may not cut his umbilical cord, one may not carry him from place to place, but rather, his mother leans over him and nurses him. One who carries him is like carrying a stone on Shabbat. If he was born in the seventh month and it is uncertain whether he was born in the eighth month, one may not desecrate Shabbat for his sake, one may not cut his umbilical cord, one does not bury his placenta, and one does not carry him from place to place.
But if it is certain that he was born in the seventh month, he is alive; one may desecrate Shabbat for his sake. One cuts his umbilical cord and buries his placenta so that the infant will not be cold, and one carries him from place to place.1From Tosefta, Shabbat 16:4. It contains only a short reference to the laws mentioned here. Why may one desecrate the Sabbath for one born in the seventh month?
It is because he is viable. But one born in the eight month, his months of gestation were not completed and it is not viable.2There was a belief in the ancient world that a baby born after seven months was more viable than a baby born after eight months. Therefore, one may not desecrate Shabbat for its sake. They3The scholars of the nations of the world. asked Rabbi Abbahu: From where is it derived that one born in the seventh month is viable?
I will bring an allusion for you from your own language: Live [zeta] – seven, go [eta] – eight.4The letter zeta represents seven in Greek, and it connotes life in several expressions. The letter eta represents eight and means go, which is interpreted as a reference to death. Which is one born in the eighth? It is one whose nails and hair are not complete.
Rabban Shimon ben Gamliel says: Anyone who does not live thirty days, his months of gestation were not completed, but it is stillborn. Why? The opinion of Rabban Shimon ben Gamliel was based on the words of the Torah, as the Omnipresent commanded to count the firstborn in order to redeem them, only after thirty days. That is what is written: “Count every [firstborn] male [of the children of Israel from one month old and above].”
“And take the number of their names” – He lifted up their heads, because the firstborn incurred liability to be executed due to the act of the calf.5The verse refers to the count of the firstborn as "lifting up their heads" to indicate that on the one hand they were being honored by being counted separately, but on the other hand they had been liable for having their heads removed, i.e., execution, for participating in the sin of the Golden Calf.