Testosterone is a hormone that is produced primarily in the testicles for men and the ovaries and adrenal glands for women. This hormone is essential to the development of male growth and masculine characteristics. For women, testosterone comes in much smaller amounts. Testosterone production increases about 30 times more during adolescence and early adulthood. After early adulthood, it’s natural for levels to drop slightly each year. Your body may see a one percent decline after you’re 30 years old.