The hormone cannot be given orally because it can be metabolized by the liver when administered orally. In the Manchester study, testosterone is put into the body via a patch. A pill loaded with progesterone is taken daily, the dual hormone combination which stops sperm production entirely in two to three months, with few side effects. The gauge is zero sperm count. And if you don't have any sperm, you don't get anyone pregnant.
Progesterone is a hormone naturally found in both sexes.
One in five male subjects reports an increase in appetite, though they don't actually eat more. Increased desire to eat is reported by women during pregnancy, also thought to be caused by increased progesterone levels. Glenn Ketchen, age 32, is keen on the method, which takes two to three months to reach a zero sperm count. I can only see positive things from it. Like most of those who responded to ads for the study, the system is most suitable for couples in a committed, monogamous relationship who want to delay having children.