Both clomiphene (taken daily as a pill ) and hMG injected two to three times a week, prompt the pituitary gland or hypothalamus (the part of the brain that regulates basic functions such as temperature) to make more luteinizing hormone and follicle-stimulating hormone. These hormones tell the testicles to produce testosterone and, possibly, more sperm.

Some studies cite an estimated 20 to 25 percent pregnancy rate for couples when the man has used fertility drugs — low compared to the rates for women on fertility drugs (20 to 60 percent). But even that number loses some of its punch when you consider that it's about the same rate infertile couples battling a low sperm count or poor sperm quality can expect for a spontaneous pregnancy with no treatment at all.