Anovulatory cycle In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia, dysfunctional uterine bleeding). Normal menstrual bleeding in the ovulatory cycle is a result of a decline in progesterone due to the demise of the corpus luteum. It is thus a progesterone withdrawal bleeding. As there is no progesterone in the anovulatory cycle, bleeding is caused by the inability of estrogen — that needs to be present to stimulate the endometrium in the first place — to support a growing endometrium. Anovulatory bleeding is hence
Menstrual cycle extra-pair flirtations and demonstrate a preference for extra pair copulation. Preferences for voice pitch change across the cycle. When seeking a short term mating partner, women may prefer a male with a low voice pitch, particularly during the fertile phase. During the late follicular phase, it is common for women demonstrate a preference for mates with a masculine, deep voice. Research has also been conducted on the attractiveness of the female voice throughout the cycle. During their most fertile phase of the menstrual cycle, there is some evidence that female voices are rated as significantly more attractive. This effect is