With headlines reading "The risk-free pill for men", Australian researchers are hailing their scientific breakthrough.
The research team led by Professor David Handelsman from the ANZAC Research Institute in Sydney involved a whopping 55 couples. During the 5- year trial none of the women became pregnant and none of the males experienced side effects.
The men were given injections of progestin (a synthetic progesterone not without its side effects when used by women). Progesterone levels can inhibit production of both testosterone and oestrogen in the body and a natural progesterone can, for example, be useful in the treatment of prostate cancer.
With the testosterone limited, the sperm production stops. However, since males need their testosterone levels for normal function, it has to be replaced and an implant of synthetic testosterone is used under the skin of the abdomen, returning libido without the sperm.
Apparently it takes about 7 months for normal service to be resumed after stopping the treatment.