Along with the above-mentioned sexual hormones, scientists, in the recent times, tend to associate pheromone with sexual attraction as well. Pheromone, odor produced by an animal that affects the behavior of other animals. The way pheromones work is analogous to the way hormones in the body send specific chemical signals from one set of cells to another, causing them to perform a certain action. The study, led by psychologists Kathleen Stern and Martha McClintock at the University of Chicago in Illinois, appears to demonstrate that women's underarm odors can change the timing of other women's reproductive cycles. This means that humans can affect each others behavior (including sexual behavior) by secreting odors, pheromones.

Progesterone, hormone formed by the granuloma cells of the corpus luteum of the ovary. The corpus luteum is a structure in the ovary that develops at the site where a mature egg was released at ovulation. Therefore the level of progesterone rises in the second half of the menstrual cycle. If the released ovum is not fertilized, production of progesterone falls just before the onset of the next menstrual cycle and the corpus luteum degenerates. Progesterone was isolated and crystallized by three independent groups of investigators in 1934. It is a steroid hormone, a compound possessing the same chemical nucleus as the female estrogenic hormones and the male androgenic hormones, as well as cholesterol and adrenal steroid hormones.

The principal function of progesterone is the preparation of the mucous membrane of the uterus for the reception of the ovum. The hormone also stimulates the formation of sac like structures in the lacteal glands in preparation for their function of producing milk, and inhibits the release in the pituitary of prolactin hormone. Formation, functions and development of progesterone in a woman's body have certain distinct features. Women are born with a finite number of ovarian follicles that develop into eggs. The process of ovulation, in which an egg is released from the ovary, is regulated by several sex hormones. As a woman matures and passes through her reproductive years, an egg is released each month and her supply of eggs gradually decreases.

As menopause approaches, ovarian follicles gradually become less sensitive to the hormones that control ovulation, follicle stimulating hormone (FSH) and hormone (LH), increasingly disrupting egg development and ovulation. The ovaries produce less estrogen, which directs the growth of the uterine lining during the first part of the menstrual cycle. Even when ovulation continues to occur, the decreased sensitivity to LH causes problems in the development and function of the corpus luteum (the ovarian follicle after ovulation). This leads to deficiencies in the production of progesterone, the hormone that controls the second half of the menstrual cycle.

The hypothalamus, the part of the brain that controls hormone production and regulation, recognizes these hormone deficiencies and signals the pituitary gland, located in the base of the brain, to increase production of FSH and LH. The reproductive organs are often ascribed credit for human sexual attraction. However, it has been proved by many scientists that sexual attraction begins in a pea-sized structure called the hypothalamus deep in the primitive part of the human brain. This tiny bundle of nerves sets off an exciting chain of events when one person perceives another to be sexually attractive.

The hypothalamus instantly notifies the pituitary gland, which rushes hormones to the sex glands. The sex glands, in turn, promptly react by producing estrogen, progesterone, and testosterone the sex hormones, which are responsible for the sexual desire. Within seconds, the heart pounds, muscles tense; he or she feels dizzy, light-headed, and the tingling of sexual arousal. This chemical driven high induces moods, which swing from omnipotence and optimism to anxiety and pining. A malfunctioning hypothalamus can have bizarre effects on ones romantic love life, including irrational and distorted romantic choices, obsessions, idealization, and separation anxiety. The height of romantic passion creates illusions of well-being, feelings of possessiveness, and happily-ever-after fantasies within the psyche of the new lover.

On the darker side of infatuation, jealousy and blind rage may surface as well (Donahue, 1985). An increase in sexual activity around the time of ovulation and another smaller increase around menses may be to hormones. The peak in behavior may coincide with increased estrogen levels. Right before ovulation, the follicles are secreting high amounts of estradiol. High amounts of androgen's are secreted and then converted to estradiol. It could be that testosterone is the best aphrodisiac and may be much stronger in women than men.

Considering the facts mentioned above, it can be concluded that progesterone occupies a special place in the row of sex hormones. In the same manner as testosterone is responsible for stimulating the development of the male secondary sex characteristics after puberty, causing growth of the beard and pubic hair, development of the penis, and change of voice, estrogen for controlling the growth of the lining of the uterus during the first part of the menstrual cycle and increasing the sexual attraction, progesterone is known for decreasing the sexual desire.