Clomiphene in male infertility (CIMI) trial: A double-blind randomised placebo-controlled trial of clomiphene in normogonadotrophic idiopathic male infertility

Infertility affects around one in six couples, and in many cases the cause lies with the male partner. Low sperm count (oligozoospermia) is a common finding, but when no underlying hormonal or genetic cause can be found — called idiopathic male infertility — treatment options are limited. Clomiphene is an oral medication that stimulates the release of hormones that signal the testes to produce more sperm. It is widely used off-label for this purpose, but solid evidence from a well-designed randomised trial has been lacking. This Phase 3 double-blind trial randomly assigns men with unexplained low sperm count to take either clomiphene or a placebo tablet once daily for 6 months. Both groups also take a men's fertility multivitamin. Sperm count and quality are tested regularly throughout the study to determine whether clomiphene genuinely improves outcomes. You may be eligible if you are a man aged 18 to 50, have been trying to conceive (with a female partner) for at least 12 months without success, and have had at least two semen analyses showing a low sperm count. You must not have had a known genetic or hormonal cause of infertility, and you should not currently be smoking or using testosterone or other hormonal medications.