Musannaf Ibn Abi Shaybah

Hazrat Mughira narrates that I asked Ibrahim, "A woman with a large head was sleeping with her child, and in the morning the child was found dead. (What is the ruling for this?)" He replied, "The purification for her soul is that she should pay the expiation: either free a slave, or fast continuously for sixty days." I asked, "What if she gets menstruation during the fasts?" He replied, "This is something necessary for women. When the menstruation ends, she should make up the missed fasts of those days (she does not need to fast all sixty days again)."

Hasan says that if a woman accidentally kills someone and then observes fasts (as expiation), and she gets her period, then she should make up those days later.

Hazrat Ibn al-Musayyib says that if a woman is fasting and then she gets menstruation, she should complete the remaining fasts later.

Hasan says that if a woman vows to perform i'tikaf and then menstruates during those days, she should make up the days she missed due to menstruation later.