Women produce testosterone naturally, secreting the hormone from their ovaries and adrenal glands. It's key in ovarian function, which means that women with proper testosterone levels ovulate regularly. Testosterone also improves bone strength, elevates mood and is even thought to stimulate sexual appetites [source: Shmerling]. According to a recent study by scientists in Italy, women who received small doses of extra testosterone reaped a number of benefits [source: Hunter]. In addition to greater muscle strength and increased endurance, testosterone supplements also reduced insulin resistance, which is a precursor to diabetes. The news is especially promising for older women who, like men, experience a decline in hormone production as they age.
But striking just the right balance of male hormones is tricky business, especially for women who'd like to increase their pregnancy odds -- which we'll explore on the following page.