If you’re over age 35 and you don’t yet have children, you’ve probably had at least one interfering person remind you that you’d better hurry up because your fertility will decline. No one ever says that to men, of course. Menopause is like a ticking time bomb for women who want to start a family, but men don’t have the same finish line for their fertility.
Or do they?
Men can produce sperm throughout their lives, so there is no “male menopause” when men can’t have children any longer. But that said, studies have shown that male fertility does decline with age.
If a man is over age 45, it can take five times longer for he and his partner to conceive than if he was aged 25 or under. When the man is over 40, he and his partner are 30% less likely to conceive during a 12-month period than if the man is under 30.
Male age affects IVF success rates too. One study found that when both the man and the woman are aged 35-39, they have a conception rate of 29%, but that drops to 18% if the woman is aged 35-39 but her partner is five or more years older.
Women tend to see their fertility drop off steeply in their late 30s and 40s, but for men, fertility lessens much more gradually, and from a later age. Male fertility generally starts to fall in their 40s and through their 50s.
A French study found that women’s reproductive capability drops from age 35, but for men it’s only from about age 40. Other research concluded that before age 34, there was no noticeable change in sperm concentration, sperm motility, sperm morphology, or sperm volume, but that after 40, sperm concentration and sperm morphology had both declined.
There are two main ways that male fertility can decline over time:
- Changes that affect the libido and cause erectile dysfunction (ED)
- Changes to sperm and semen production
Scientists have also found that as men age, sperm shows increasing DNA fragmentation, which in turn increase the chromosomal defects that trigger miscarriage.
When men struggle to achieve erection, it’s referred to erectile dysfunction. Without an erection, a man can’t naturally ejaculate the sperm which fertilize the egg and achieve conception. ED can have a number of causes, including insufficient testosterone and poor blood circulation. The risks of severe ED rise 300% between the ages of 40 and 70, and those of moderate ED by 200%.
As men get older, their hormonal balance changes and testosterone levels drop. The decline begins at around the age of 40, which is much later than the age when female fertility begins to decline, but it’s still significant.
Testosterone is the hormone that controls men’s libido, ability to ejaculate, and the ability to achieve and hold an erection. Total testosterone declines at around 0.8% per year, and sex hormone-binding globulin (SHBG) increases at 1.6% per year, which scientists speculate further reduces testosterone levels.
By now, scientists agree that sperm quality decreases with age, but there’s less agreement about exactly why and how that takes place. The drop in testosterone certainly plays a role. Leydig cells in the testes generate very high levels of testosterone which produce sperm, but those Leydig cells drop in number with age.
There are a number of factors which affect sperm and semen health. (Sperm is what fertilizes the egg, and semen is the liquid which holds the sperm.) The main issues are:
- Sperm concentration (% of sperm in the semen liquid)
- Sperm morphology (shape)
- Sperm motility (ability to move to the egg)
It’s still unclear whether sperm concentration falls significantly. Some scientists even think that sperm concentration may increase slightly with age.
There are studies that show that sperm morphology can decline by anything up to 0.9% per year, with a total change of up to 18% over 20 years. Sperm shape affects the sperm’s ability to fertilize the egg. The more that it varies from the normal, the harder it will be for conception to take place. However, sperm morphology is difficult to research with confidence, because the data can vary a lot between studies.
Scientists are far more concerned about the way that changes to sperm motility affects male fertility. According to the most recent research, sperm motility could drop by 0.8%/year of age for every year of age. In fact, 40% of men aged 40-60 have low motile sperm, in contrast with just 20% of 20-30 year olds and 17% of 30-40 year olds.
Other issues that cause sperm health to decline are a drop in semen volume, and a loss of strength in vesicular function, which means that the semen is ejaculated much more weakly and doesn’t travel as far.
Women are born with a finite number of eggs, but men keep on producing sperm throughout their lives. Every time that sperm is made, it reproduces the male DNA, and with every replication there’s a risk of mutations, or DNA fragmentation. As men get older, DNA fragmentation increases.
A rise in DNA fragmentation also means a rise in chromosomal abnormalities, which can cause health defects, low birth weight, and miscarriage or stillbirth. The risk of miscarriage in the first trimester is 25% higher when the father is over 35, even if the mother is under 30. Another study found that babies born to fathers aged 45 or over were more likely to be born premature and more likely to have a low birth weight and Apgar score than those born to younger fathers. Additionally, babies with fathers aged over 55 were more likely to need assisted ventilation and to be admitted to a NICU.
Bear in mind that the older you are, the more time you’ve had to be exposed to toxins, germs, and to develop conditions that can affect fertility. The authors of one study observe that “the risk of developing a medical condition or of being exposed to environmental toxins increases with age.”
Some of the environmental issues that can affect male fertility include:
- Exposure to toxins at home or at work
- Exposure to high temperatures
- Side effects from prescription medications
- Medical conditions
Endocrine disruptors are found in many common items both at home and at work. These are materials that disrupt the release of the sex hormones which control sperm production and erectile function. Some serious endocrine disruptors include:
- Triclosan, found in many antibacterial soaps and household cleaners
- Phthalates and parabens, used in dozens of products including deodorants, laundry detergents, and air fresheners
- BPA (Bisphenol A) and Bisphenol S (BPS), used in plastics like saran wrap, plastic bottles, and mobile phone cases.
Other chemicals that affect the hormonal balance include pesticides, DDE, diesel fumes, lead, and paint thinners. Traffic fumes can also affect sperm count, motility, and vitality. .
Sperm production works best when the testes are a couple of degrees cooler than typical body temperature, but a lot of men work in hot environments like factories, garages, etc. which raise testicular temperature. When the testes are too hot, they are more likely to produce sperm that’s the wrong shape, affecting sperm motility.
Male fertility problems are often linked to other health conditions, like obesity, cancer, hypertension, heart disease, and kidney disease. Heart disease and hypertension, for example, affect vascular health and increase the risks of ED. Obesity can affect the hormonal balance. All of these conditions are more likely to affect older men rather than younger men.
Common medications like spironolactone and calcium channel blockers prescribed for hypertension, H2 blockers prescribed for stomach ulcers, and antiandrogen treatments (flutamide) for the prostate can all have side effects that affect sperm production.
Like with other health issues, maintaining a healthy weight and avoiding known toxins can make a difference to male reproductive health. If you’re having trouble conceiving, it’s also worth considering if there’s something in your workplace or home environment that could be affecting your fertility.
However, no one can (or should try to) avoid getting older, and it’s inevitable that male fertility will decrease somewhat with age. If you’re a man aged over 40 and you and your partner are struggling to conceive, it’s worth it to check if there’s anything that could be affecting your fertility levels as well as investigating female fertility.
Whether you use IVF, donor sperm, or natural conception to build your family, we hope your experience is as smooth as possible.
This article has been brought to you with the support of Gedeon Richter.