My sister and I have to different opinions on this. Do the female body have to have a monthly cycle inorder to remain healthy every month?

Normal menses? Many female athletes and dancers experience reduced periods per year and seem not to have medical problems because of it. Some birth control methods stop periods for months at a time. Whether these conditions are "healthy" is a matter of debate. Any woman experiencing irregular menses should be followed closely by her fp/gyn to make certain no problems arise.