2,048. Immersion by Day and by Night

Hilchos Issurei Biah 4:5

All blood from a woman for 33 days after the birth of a boy and for 66 days after the birth of a girl is called “blood of purity” and it doesn’t preclude a woman being intimate with her husband. Rather, she immerses herself after seven days for a boy and after 14 days for a girl and may then engage in relations with her husband even though blood may continue to flow.

Hilchos Issurei Biah 4:6

All who must immerse themselves must do so during the day except for a niddah and a woman who has given birth. Regard a niddah, Leviticus 15:19 says, “She will be in her niddah condition for seven days,” i.e., her niddah state lasts for these seven days, after which she immerses on the eve of the eighth day. Similarly, a woman who has given birth to a boy immerses on the eve of the eighth day, while one who has given birth to a girl immerses on the eve of the fifteenth day. This is because a woman who gives birth is comparable to one in niddah, as has already been discussed.