Missed period. Check home pregnancy test. If negative, you may have failed to ovulate, and your hormone levels did not properly prepare and stimulate your uterus to cause bleeding. Your period occurs when you have a decrease in Progesterone and causes the uterine lining to shed because you are not pregnant, and the uterus prepares for the next cycle. If the uterus doesn't build up a lining, it will not bleed.