Childbirth involves pain. This is an element of the decree issued against Eve after the sin of eating from the Tree of Knowledge. The Sages speak about the emotional process that this experiences entails, and women who merit a painless birth.

The students of Rabbi Shimon ben Yohai asked him: For what reason does the Torah say that a woman after childbirth shall bring an offering? He said to them: At the time that she crouches to give birth, her pain is so great that she impulsively takes an oath that she will not engage in relations with her husband. Therefore, the Torah says: She shall bring an offering.

[The verse states with regard to the mother of Moses]: “The woman conceived and bore a son” (Exodus 2:2)…. The verse serves to juxtapose her birthing him to her conceiving him: Just as her conceiving him was painless, so too, her birthing him was painless. From here it is derived that righteous women are not included in the verdict of Eve. (Nidda 31b; Sota 12a)