It differs among girls, but it usually starts around 12 or 13
Three weeks
Technically, dogs do not have menstrual cycles - only primates menstruate. However, dogs do have estrus or heat cycles, and a female dog can start cycling at about 6 months of age.
No, reptiles do not have menstrual cycles or periods like mammals do. Instead, they have reproductive cycles that are different from those of mammals.
Menstrual cycles begin at puberty. Women hit puberty at different times, just as men do. The average age for puberty is between 12 to 15 years old. Menstrual cycles usually begin somewhere within that range.
No
No, bearded dragons do not have menstrual cycles. They do not menstruate like humans or some other mammals.
No.
Menopause starts somewhere between 45-55 years old in most people, this is the start of the winding down of the reproductive cycle so menstrual cycles become irregular. When menstrual cycles stop all together can vary greatly from person to person after menopause.
because it just does.
Delayed menstrual cycles have been reported when taking Ciprofloxacin. The delay can also be caused by the urinary tract infection. Both can cause delayed menstrual cycles.
Once a month
No. Humans are the only mammals with menstrual cycles. Deer, as well as other mammals, have estrous cycles. http://en.wikipedia.org/wiki/Estrous_cycle