Should a woman who is in post-partum bleeding fast if she attains purity before the completion of forty days?
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Shaykh Ibn ‘Uthaymeen said: “Yes. As soon as a woman who has post-partum bleeding attains purity, even if that is before the completion of forty days, she should fast, if it is the month of Ramadan. She should also pray and it would be permissible for her husband to have sexual intercourse with her as she is pure and there is nothing that would then forbid her from fasting, praying or having sexual intercourse.”
Allah Knows best.