What is the ideal duration of one complete menstrual cycle?

There isn't exactly one specific ideal menstrual cycle, but under the most normal circumstances the average should be around 28 days.

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other.