The Gemara asks: What is the halakha if she then sees menstrual blood at regular intervals of thirty-day cycles? Is her time sufficient, or does she transmit impurity retroactively? Rav Giddel says that Rav says: With regard to the first time and the second time that she sees menstrual blood, her time is sufficient. After the third time, she transmits impurity retroactively for a twenty-four-hour period or from examination to examination.

The baraita further teaches, with regard to a young girl who did not experience bleeding for three typical cycles and then saw blood, and three further expected menstrual cycles passed without her experiencing bleeding and then afterward she saw menstrual blood, that her time is sufficient. The Gemara asks: What is the halakha if she then sees menstrual blood at regular intervals of thirty-day cycles?

The Gemara answers: Rav Kahana says that Rav Giddel says that Rav says: The first time that she sees menstrual blood, her time is sufficient. After the second time, she transmits impurity retroactively for a twenty-four-hour period or from examination to examination.

The Gemara asks: Who is the tanna of the baraita? The Gemara answers: Since the baraita teaches that she attains the status of a regular adult woman upon the third sighting of menstrual blood, apparently it is Rabbi Yehuda HaNasi, who said that presumption is established by two occasions.

The Gemara raises a difficulty: Say the latter clause: If she then passed three expected menstrual cycles without experiencing bleeding, and then she saw menstrual blood, she returns to the status of a young girl and her time is sufficient. In this ruling we come to the opinion of Rabbi Eliezer, who holds that any woman who passed three expected menstrual cycles without experiencing bleeding is presumed not to be menstruating and her time is sufficient. Is the baraita in accordance with the opinion of Rabbi Yehuda HaNasi or Rabbi Eliezer?

And if you would say that the tanna of the baraita is Rabbi Yehuda HaNasi, and in the case of a woman who passes three menstrual cycles without experiencing bleeding, he holds in accordance with the opinion of Rabbi Eliezer, but does he really hold in accordance with this opinion? Doesn’t the baraita state that after Rabbi Yehuda HaNasi remembered that several authorities disagreed with the ruling of Rabbi Eliezer, he said: Rabbi Eliezer is worthy to rely upon in exigent circumstances, i.e., only in exigent circumstances. The Gemara concludes: Rather, the tanna of the baraita is Rabbi Eliezer, and with regard to menstrual cycles he holds in accordance with the opinion of Rabbi Yehuda HaNasi, that a presumptive cycle is established after two occasions of seeing menstrual blood.

§ With regard to a young girl who was just starting to menstruate, the Gemara states: If she finds a blood stain between the first and second time that she sees menstrual blood, she is pure. If it is between the second and the third time, Ḥizkiyya says: She is impure; Rabbi Yoḥanan says: She is pure. The Gemara explains the reasoning behind their respective opinions. Ḥizkiyya says: She is impure, since if she had seen menstrual blood it would render her impure. Consequently, her blood stain is also impure. And Rabbi Yoḥanan says: She is pure, since she has not yet attained the presumptive status of one who sees menstrual blood. Therefore, we also do not render her impure on account of her blood stain.