Androgens are male sex hormones: primarily testosterone, DHEA, and androstenedione. They are much higher in men than in women, of course, and elevated androgens are a common symptom of PCOS, a common cause of female infertility.
But it turns out that women need some testosterone for optimal fertility. Too much is a problem, but so is too little.
The basic unit of female fertility is the follicle, a collection of cells that houses an egg. The connective tissue surrounding the follicle produces testosterone, and the testosterone produced gets passed along to the inside of the follicle. During the first half of the menstrual cycle, the pituitary produces the hormone FSH (follicle stimulating hormone), which encourages the follicle to convert the newly-minted testosterone into estrogen. Estrogen encourages the follicles to grow, and the eggs inside to develop.
Since this process starts with testosterone, testosterone is clearly a critical ingredient in female reproduction. But, too much testosterone is the hallmark of PCOS, which leads to a prolonged follicular phase (the first half of the cycle), a shortened luteal phase (the second half of the cycle), and often anovulation, irregular periods, or lack of menses altogether.
Testosterone Protects the Follicles
This study shows that testosterone also helps to protect follicular cells from apoptosis, or self-destruction. The implication is that inadequate levels of testosterone might prevent follicles from developing to the point of releasing a mature egg—just as too much testosterone leads to too many follicles developing at once. This seems to be most important several months before the follicle is ready to ovulate–which means it’s important to have adequate androgen status well before trying to get pregnant.
Does Testosterone Actually Improve Fertility Outcomes?
Women with low androgen levels who undergo IVF tend to have poorer outcomes. According to this study of women who underwent IVF (In Vitro Fertilization) treatments, testosterone made a significant impact on both clinical pregnancy and implantation rates.
According to this animal study, DHEA, the precursor for testosterone, improves ovarian reserve, which tends to decline with age. This study shows that DHEA specifically may be helpful for women undergoing fertility treatments, particularly if their ovarian reserve (measured by AMH, Antimullerian Hormone) is low.
There is a place for testing androgens for female fertility, even if PCOS is not suspected—all of the sex hormones play a role in fertility, not just estrogen and progesterone.