Both of these hormones occur in both men and women. Follicle stimulating hormone, or FSH, has a role in men's reproductive health very similar to its role in women. In women, FSH causes the formation of a tube to deliver a single mature egg. In men, FSH causes the formation of hundreds of millions of tubes to deliver hundreds of millions of sperm. FSH is important to both male and female fertility, although men's bodies contain vastly less of this hormone. In men, luteinizing hormone, also known as LH, triggers the production of testosterone. Vitex reduces LH levels, so it also reduces the production of testosterone. When a man takes vitex, his testosterone levels decrease, and in some cases, the testicles can shrink. Vitex controls a man's sex drive, but it also cripples male fertility. In women, vitex is usually beneficial for fertility.
The changes in LH and FSH levels initiate a series of hormonal changes that increase a woman's production of progesterone and decrease production of both estrogen and testosterone. Increasing the production of progesterone stimulates the maturation of a follicle in the ovaries that will, at ovulation, release a single egg. Decreasing the production of estrogen stops the swelling of endometrial tissue that can become lodged over the fallopian tubes that release the egg into the uterus. With less estrogen to stimulate "misplaced" tissue, the egg has a greater chance of reaching its destination in time for conception to occur. Vitex alone restores fertility in about 30% of women who take it. The herb does not contain any actual hormones, bioidentical or otherwise. It simply influences the way a woman's body makes hormones. If there are other health issues, vitex will not be enough.
Even when vitex does not restore fertility, however, it may relieve acne and hair growth caused by PCOS, and it may raise progesterone levels enough that other methods, combined with this herbal treatment, will restore a woman's ability to conceive. Just be sure that the intended father has absolutely no contact with the herb.