If you and your devoted are dancing around the idea of having a baby, odds are you're keeping track of your biological clock. Sure, you know how your age comes into play, but what about the candles on his birthday cake? Should you also be factoring his years into the equation? With 60-somethings like Billy Joel and Jeff Goldblum expanding their broods, it's easy to dismiss your guy's age.
But you shouldn't shrug it off completely, says Harry Fisch, a urologist and director of the male reproductive center at New York-Presbyterian Hospital/Columbia University Medical Center. A leading male fertility expert, Fisch literally wrote the book on the subject: The Male Biological Clock: The Startling News About Aging, Sexuality, and Fertility in Men. our site sat down with him to find out what you need to know about the fertility of your other half.
What's the biggest myth about men and fertility?
The biggest misconception is that men age and nothing changes. Men feel that no matter what they do, everything will be the same. That's just not true. Men's fertility does decline with age.
In a study published in the journal Fertility and Sterility, researchers interviewed nearly 2,000 women to find out how long it took them to conceive. Among women 35 and older, those whose male partners were 45 and older took five times longer to conceive than those whose partners were 25 and younger.
The researchers also looked at what happens when young women (age 25 and under) have children with men 45 and older. The researchers found a fourfold increase in the time it took couples to conceive – meaning the man's age was a factor independent of the woman's age.
How do men's and women's biological clocks differ?
They are distinctly different. A woman's egg supply is set before birth, declines dramatically even before she's out of the womb, and by the time she reaches menopause, most of her eggs are gone. In addition to that, a woman's left not just with fewer and fewer eggs as she ages, but with a higher concentration of abnormal ones.
On the other hand, a man produces sperm throughout his life. He experiences a slight decline in fertility as he gets older, but his semen doesn't lose its concentration.
So, for men there's no age limit when it comes to fathering children, which is why it's not unusual to see older men with young kids. But for women, age plays a huge factor in the ability to get pregnant.
How are men's and women's biological clocks similar?
As a woman ages, there's a decline in her body's production of the female hormone estrogen, a decline in fertility, and a higher risk that her baby will have genetic problems. As men get older they see a decline in the male hormone testosterone, a decline in fertility, and a greater chance of fathering children with genetic problems.
So just because he can make sperm doesn't mean it's high-quality sperm. As men age, the volume, motility (speed), and quality of their sperm decline.
A number of years ago, the journal Fertility & Sterility published one of the largest reviews of male fertility to date. The authors found that between the ages of 30 and 50, the average man's sperm declines by up to 30 percent in volume, swims up to 37 percent slower, and is five times more likely to be misshapen.
Shape is important because it correlates with the sperm's genetic content. A higher number of misshapen sperm equals a greater potential for genetic abnormalities.
Are genetic problems linked to older men?
Some genetic abnormalities, like dwarfism, have long been associated with paternal age, but we didn't give these problems much scientific attention because they're relatively rare.
In recent years, clinical trials have found links between the father's age and more common genetically related conditions, such as Down syndrome and schizophrenia.
Overall, the risk is highest when both parents are over 35. Since the number of births to parents older than 35 has more than doubled in the past two decades, this is a valid concern.
A study published in the Journal of Urology found that the rate of Down syndrome births doubled among women ages 35 to 39 if their partner was also over age 35. (However, if a woman is 35 or older, odds are she's going to have an amniocentesis or CVS, either of which would detect Down syndrome.)
Paternal-age risk factors aren't really an issue for women 35 and under because the ovaries have a built-in mechanism that repairs damaged DNA delivered by the sperm. But that safety net starts to break down after she turns 35.
Should older men be allowed to donate sperm?
On the evidence that sperm from older men is more likely to have genetic abnormalities, some European countries have prohibited men from becoming sperm donors after they reach a certain age. But I think that as long as a man has well-shaped sperm and a good sperm count, he should be entitled to donate sperm.
That said, it becomes harder and harder to meet those criteria as you get older. And even putting age aside, it's very difficult to qualify as a sperm donor.
Only 5 percent of men who apply to become donors are accepted because there are so many rules and regulations. For example, if you have a tattoo or a body piercing, you're automatically disqualified because there's a chance you've been exposed to hepatitis B or C.
Does weight affect male fertility?
Yes. In fact, one of the best things a man can do to protect his fertility is whittle his waist. Obesity in general is associated with male infertility.
Additionally, a man's waist size is directly proportional to his testosterone level. All fat cells break down testosterone, but belly fat destroys testosterone the fastest, because visceral fat is broken down into estrogen more quickly than other types of fat. Estrogen basically cancels out testosterone in this situation – so the higher a man's waist measurement, the lower his testosterone level.
Plus, men who are overweight often lead sedentary lives and have other health problems. For instance, a waist size of 40 inches or more is an independent risk factor for heart disease in men, and because heart disease slows blood flow throughout the body, what's bad for the heart is bad for the penis.
If you're a man who had a 34-inch waist when you were 20 and you're at 40 inches now, you're in trouble. In most men, 5 pounds equals 1 inch around the waist.
Aim for a healthy weight, but don't go overboard. Men who are too thin also struggle with low testosterone: If the body isn't getting sufficient nutrients, it often shifts into a conservation mode and produces fewer sex hormones.
What can men do to turn back their clock?
The best thing about the male biological clock is that it's usually reversible. Losing weight, having an infection treated, or getting a blockage cleared up can sometimes do the trick. But you need to be tested before you can be treated. So if a couple is having problems getting pregnant, it's important for the man to see a specialist.
When it comes to infertility, 40 percent of the time the problem lies with the man, in another 40 percent of cases it's the woman, and 20 percent of the time both partners have contributing factors or the cause is unknown. But male infertility is almost always easier to diagnose and remedy than female infertility, so it's always worth starting with him.
One of the biggest causes of male infertility is infection in some part of the reproductive tract, such as the prostate. A low-grade infection can go undetected for years while silently damaging or killing sperm. I can't tell you how many pregnancies I've seen happen just by putting the man on antibiotics. Other common causes of male infertility are clogged ejaculatory ducts and enlarged veins in the scrotum, called varicoceles. All of these conditions are treatable.
What do other top fertility experts have to say?
"We know a lot less about the male biological clock than about the female version, and for a long time men didn't want to admit it was an issue. Denial was easy because men don't have a barometer for fertility the way women have a period every month. But it's become clear that there is a hormonal decline as men get older."
– Paul Shin, urologist and director of male infertility treatment at George Washington Medical Center in Washington, D.C.
"The concept of a male biological clock is appropriate – as men age, their testosterone levels go down – but the change is much less dramatic than women's loss of estrogen. By age 45, 99 percent of women are infertile while most men are still fertile at age 60 and beyond. Still, men who want to conceive later in life should have a semen analysis and not assume they are fertile."
– Mark Leondires, fertility specialist and medical director of Reproductive Medicine Associates of Connecticut
"One of the best markers we have of the male biological clock is an increase in DNA-damaged sperm. At age 25, only 5 percent of a man's sperm has DNA damage; by age 35, that percentage has grown to 20 percent. That's a fourfold increase in just ten years. As the percentage of damaged sperm increases, the odds of fertilization decrease."
– Narendra Singh, associate professor in the Department of Bioengineering at the University of Washington, Seattle
"Using the male biological clock to describe a man's fertility as he ages is a bad choice of words. The phrase conjures up a false sense of finality. If you look at the percentage of men over age 50 with low testosterone, it's about 15 percent. In comparison, nearly 100 percent of women over age 50 have low estrogen."
– Larry Lipshultz, professor of urology and director of Male Reproductive Medicine and Surgery at Baylor College of Medicine in Houston and chairman of the American Urological Association's Council on Reproductive Health
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