Communication of impurity from the milk of a nursing mother who is a niddah: Keritot 13a-b
Communication of impurity from the milk of a nursing mother who is a zavah: Keritot 13a-b
A Sfek-Sfeika case of doubt, regarding transmission of impurity: Doubt whether a child nursed enough milk to communicate impurity, and doubt whether he consumed it in a short enough period of time for this to be considered significant consumption: Keritot 13a
Other
Special fasts for the benefit of sailors, travellers in the desert, infants, and pregnant and nursing women: Taanit 27b
The kosher status of a woman's milk: Ketuvot 60a; Keritot 22a