A woman was having a difficult labor, and she was moved from one house to an-other. The first [house] is tamei because of doubt, and the second [house] is certainly [tamei]. R’ Yehudah said: When [does this apply]? In a situation in which she walked with assistance; but if she was able to walk [without assistance], the first [room] is tahor, because once the womb is open, it is impossible to walk. A stillborn child does not open the womb, unless [his] head is round like [the size of] a whorl.