We might be tempted to think that when the levitical law labeled something as unclean it meant sin was involved. However, do not think that way. Leviticus 15:19-24 address the issue of, “If a woman has a discharge, and the discharge from her body is blood…” (Leviticus 15:19-24). The earlier part of the chapter addressed discharges from a man.
The Lord went on to explain the regulations concerning that discharge from the woman and how long she would be unclean. Notice that the discharge was a normal and natural thing, but there was just uncleanness associated with it.