All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Scholars stated that there are two signs, either of which indicates the end of menstruation or post-partum bleeding:
1- Cessation of blood: this means that when a woman wipes her vagina with a piece of cotton or white cloth, she does not find any trace of blood.
2- Emission of white discharge which marks the end of menstruation or post-partum bleeding. It is the strongest evidence with which a woman realizes that she has become pure. It is narrated that women used to send pieces of cotton with yellowish traces to ‘Aa’ishah and she would say to them: "Do not hasten until you see the white discharge,” meaning purification from menstruation." [Maalik]
These are the two signs of purification regardless whether the newborn is male or female. This ruling is general and the scholars did not provide a different ruling in this respect.
Allaah Knows best.