Hormones & cycle. Menstrual cycle is regulated by fluctuation in levels of women's hormones. Depending on where one is in the cycle, different methods of pushing off menses may be used. In the 1st week, regular birth control pills may be taken. By skipping last week's "placebo" pills, cycle may be extended as needed. In the 2nd half of the cycle, taking continuous progesterone results in menses being pushed off.