A Primer on Male Infertility
Part 1 in a 2-part series on male infertility and sexual health
If a couple is unable to conceive naturally after one year of unprotected intercourse, that couple is deemed to be infertile. But does the problem lie with the male or the female?
Perhaps surprisingly, male infertility is estimated to contribute to 50 percent of all infertility cases, says Dr. James Kashanian, Director of Male Sexual Health and Assistant Professor of Urology and Reproductive Medicine at Weill Cornell Medicine, and it’s the sole cause of a couple’s infertility in 20 to 30 percent of cases. Sometimes, though, no cause can be found.
“Unlike women, who become infertile starting in menopause, there is no cutoff age range for a man to be unable to conceive naturally,” Dr. Kashanian says. “That said, age-related changes occur in men as they age. Similarly, various medical problems, illicit drugs, medications and environmental exposures can affect male reproductive hormones, sperm counts and sperm quality.”
What causes male infertility?
Male infertility can be caused by:
- low sperm production, abnormal sperm function or blockages that prevent the delivery of sperm
- hormonal issues
- genetic anomalies
- illnesses, injuries or chronic health problems
- lifestyle choices
- environmental exposures
“Some of these can be reversed, but others can have long-lasting effects, such as certain types of chemotherapy that are toxic to the male reproductive system,” he says. “We have seen that even environmental factors, ubiquitous in western countries, can penetrate the testicles and semen and affect fertility in men.”
The effects of a man’s age
“We know that there’s an age-related decline in testicular function as men age,” says Dr. Kashanian. “This includes as much as a 1 percent decline in testosterone levels per year, starting sometime during a man’s 40s.
“We also see a decline in various semen parameters as men age,” he continues. “These include semen volume, along with sperm motility (the ability of sperm to move) and morphology (the size, shape and appearance of sperm). We also see increased sperm aneuploidy—one or more extra or missing chromosomes in sperm cells—in advanced paternal age.” This last abnormality may be caused by aging-related chronic conditions, such as diabetes and vascular disease, which erode the body’s ability to repair itself and may lead to a decrease in male hormone levels.
How does advanced paternal age affect a man’s offspring?
“We haven’t been able to specify what qualifies as advanced paternal age—at least not yet—but many of us in the field would estimate it to be between 40 to 50 years old. Beyond that, there is a significant increase in risk for men in their seventh and eighth decades of life, especially for their offspring.
The children of older fathers are at greater risk for autism spectrum disorders, schizophrenia, ADHD, cardiovascular problems and rare genetic diseases.
Getting tested for infertility
The best way to assess male fertility is through semen analysis. That alone will not fully predict a man’s ability to conceive, but it will provide a rough evaluation of a man’s semen and sperm, Dr. Kashanian says. “A lot can be learned from semen analysis, and if abnormalities are present, further evaluation is warranted.”
Many factors can affect a male’s fertility. However, varicoceles—enlarged veins in the scrotum—are the most common cause of infertility. These are present in 20 percent of men. Although they don’t always cause infertility, they are easily treatable with surgery.
Another major cause of infertility is azoospermia (the absence of sperm in the ejaculate). Azoospermia can be obstructive (caused by a blockage) or non-obstructive (caused by poor sperm production).
Blockages may originate with a vasectomy, infection, pelvic surgery or a prostate cyst. They may also be congenital—something you’re born with—such as the lack of a vas deferens, the duct that transports sperm out of the testes.
“Roughly 1 percent of men have non-obstructive azoospermia, possibly caused by genetic abnormalities, medications or a variety of medical conditions,” he says.
“We can often distinguish between obstructive vs. non-obstructive azoospermia via a thorough physical exam and laboratory tests. In either case, surgery is required to extract sperm from the testicle or epididymis (another part of the male reproductive system where sperm are stored). The extracted sperm can be used later for in vitro fertilization (IVF).
A common genetic cause of infertility in men
Here’s a quick review of human genetics and gender.
All of us have 46 chromosomes. Males have one X chromosome and one Y chromosome, while females have two X chromosomes. The Y chromosome carries the genes that are responsible for producing sperm.
Some men may have an extra X chromosome, or XXY. That’s called Klinefelter syndrome, and it occurs in approximately 1 in 500 males.
Children and adults with Klinefelter syndrome may not have obvious physical differences, Dr. Kashanian explains. “There may be growth or developmental concerns in early childhood, best dealt with by specialists in endocrinology, developmental/behavioral pediatrics or speech/language therapy. The majority of men with this abnormality will have azoospermia. At Weill Cornell Medicine, we have a multi-disciplinary Klinefelter Syndrome Care Center for children and adults with Klinefelter syndrome.”
If you suspect you are infertile, see your doctor for a referral to an infertility specialist. There are tests that may tell if you have fertility problems. When it’s possible to find the cause, treatments may include medications, surgery or assisted reproductive technology. Happily, many couples treated for infertility are able to have babies, Dr. Kashanian says.
Look for part 2 in this series, which will focus on male sexual health.