Corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively. It also produces relaxin, a hormone responsible for softening of the pubic symphysis which helps in parturition. If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 10 days in humans). It then degenerates into a corpus albicans, which is a mass of fibrous scar tissue. The uterine lining (endometrium) is expelled through the vagina (in mammals that go through a menstrual cycle).
Menstrual cycle by women during the peak of their fertility in the menstrual cycle. Moreover, women may demonstrate preference for men with a scent that indicates developmental stability. With regard to women's smell across the cycle, some evidence indicates that men use olfactory cues in order to know if a woman is ovulating. Using a rating of women's odors, women who are ovulating have been rated as more attractive by men. Men demonstrate preferences for the scent of fertile women. Preferences for facial features in mates can also change across the cycle. There has been no difference found in preference for long-term