תלמוד על שבת 258:6

So is the Mishnah: “Everything that is necessary for a woman in childbirth one does on the Sabbath.⁶⁰In this reading the Mishnah does not anticipate the topic of the next Chapter; also the statement of Mishnah 18:3 in the original text is repeated in 19:2.” It was stated:⁶¹Tosephta 15:3, Babli 129b. In these Babylonian sources the reason is given that the baby might catch a cold if the placenta remains exposed. “Concerning the placenta on the Sabbath, the rich women hide it in oil, the poor ones hide it in straw and sand. Both hide it in the earth, to give a pledge to Earth⁶²To ensure that Earth will have space ready for burial if the newborn should need it at the end of his life..”