"If you have no sperm, you're not going to be able to conceive," says Jon Pryor, MD, chair of the department of urologic surgery at the University of Minnesota. "When you have a sperm count of less than 5 million, it's going to be very difficult. But does someone who has a sperm count of 20 have more difficulty conceiving than someone at 50 or 60? Probably not."
Of course, sheer numbers are not the only consideration. Quality counts, too. For example, sperm shape, as well as sperm motility, or movement, also play important roles in conception. Reproductive specialists suspect that other factors unrelated to sperm health are also at work in fertility, but these are not yet understood.
"We're in our infancy in figuring out why people have trouble conceiving," Dr. Pryor says. "The first things that hit you over the head are the number, movement and shape of the sperm, but there are probably hundreds of different biochemical and molecular reactions that happen for fertilization and a successful pregnancy to occur."
Sources of Low Sperm
Still, there is no doubt that sperm count is important, so men who are interested in fatherhood should do what they can to keep counts high. The most common identifiable cause of low sperm count is variococles, which are dilated, or expanded, veins in the scrotum. Varicocles are seen in about 15 percent of all men and 40 percent of men with infertility.
It's theorized that variococles hurt sperm production by heating up the testicles, but this effect is not completely understood. Dr. Pryor says that surgically blocking the dilated blood vessels so the blood is re-routed improves sperm counts about two-thirds of the time.
