Society considers infertility to be primarily a women’s issue. But findings show that up to 50% of infertility cases have a significant male component, and about 20% of infertility cases are solely male-related, according to Barry Witt, MD, a board-certified reproductive endocrinologist who is the medical director of WINFertility, which bills itself as family-building clinic. Witt is also an associate professor in the reproductive endocrinology and infertility division in the department of obstetrics and gynecology at the Yale School of Medicine.

“Although women typically initiate the evaluation of their infertility with their gynecologist or reproductive endocrinologist, it is critical to test the male with a semen analysis to see whether there are any male-related fertility issues that need to be addressed,” Witt says.

Many people believe that men are fertile forever, but this is a myth. Beginning at age 35, aging is associated with a significant decline in semen’s reproductive potency—in terms of sperm volume, motility and its size and shape. “This is also reflected in decreased pregnancy rates (25% to 35% lower in partners of older men) and a longer time [for women] to conceive,” Witt explains. “The risk of miscarriage is higher if the man is over 45. There has also been a direct link found between the man’s age and an increased risk for autism, schizophrenia and some genetic mutations in their offspring.”

Another myth is that frequent ejaculation decreases male fertility. But in men with normal semen quality, sperm concentrations and motility remain normal, even if they ejaculate every day. “In fact, in men with significantly reduced sperm counts, the sperm concentrations and motility may be highest with daily ejaculations,” Witt says. “Longer intervals of abstinence are actually associated with poorer semen parameters.”

Some people believe that taking testosterone can enhance a man’s fertility. However, testosterone has been studied as a male contraceptive. For men with low testosterone levels who are not planning on having children, taking supplemental testosterone can boost libido and energy.

“But the hormone suppresses the pituitary gland and shuts down sperm production, often resulting in very low or absent sperm in the ejaculate, which can last for many months after discontinuing the testosterone supplementation,” Witt says. “Men who are planning on creating a pregnancy should not take testosterone.” (Medications that increase men’s testosterone level without suppressing sperm production are available.)

Men and women who smoke double their risk for infertility. “While most men know that quitting smoking has obvious health advantages, many don’t realize how harmful cigarettes can be to fertility,” Witt observes. “Smokers have a significantly lower chance of creating a pregnancy each month, and smoking as few as five cigarettes per day has been associated with lower fertility rates.”

In addition, men with overweight may also experience decreased sexual desire, and men with morbid obesity may find it difficult to perform intercourse effectively. “Diet and exercise are important in trying to bring down the BMI [body mass index] to a more normal level, which will improve the semen parameters and the libido,” Witt advises.

To learn more about male sexual health, read “Men and Sexual Health” and “An Orgasm a Day May Boost Sperm Health.”