It adds extra effects like dripping blood, reduced speech and NPC comments to the fertility mode's menstruation cycle.     To stop the bleeding sanitary napkins requires which can be crafted at a tanning rack with linen wraps or may be found in shops. They will automatically remove from your inventory and used when needed.   By default, a new one is needed every four hours but it can be changed from the MCM menu or by changing this global variable:   zzzmrt_Hou