Positive commandment · Mitzvat Aseh #76 of 613
For a woman who gave birth to offer a sacrifice after she becomes purified
להקריב היולדת קרבן אחר שתטהר
The verse · Vayikra 12:6
וּבִמְלֹאת יְמֵי טׇהֳרָהּ לְבֵן אוֹ לְבַת תָּבִיא כֶּבֶשׂ בֶּן־שְׁנָתוֹ לְעֹלָה וּבֶן־יוֹנָה אוֹ־תֹר לְחַטָּאת אֶל־פֶּתַח אֹהֶל־מוֹעֵד אֶל־הַכֹּהֵן
“And when the days of her purifying are fulfilled, for a son or for a daughter, she shall bring a lamb of the first year for a burnt offering, and a young pigeon, or a turtledove, for a sin offering, to the door of the Tent of Meeting, to the priest:”
The Rambam’s words
For a woman who gave birth to offer a sacrifice after she becomes purified, as [Leviticus 12:6] states: "And after the conclusion of her pure days...."
להקריב היולדת קרבן אחר שתטהר, שנאמר: "ובמלאות ימי טהרה" (ויקרא יב,ו).
Why · Sefer HaChinuch #168
Sacrifice of the woman that has given birth
“It is from the roots of the commandment [that it is] in order that she be aroused by action to give thanks to G-d, blessed be He, Who saved her from the pangs of her birth, which is a miraculous thing.”
Who & when
“And [it] is practiced at the time of the [Temple] by females.”
Where in the Mishneh Torah
Hilchot Offerings for Those with Incomplete Atonement הלכות מחוסרי כפרה