About 7% of men worldwide experience infertility, based on a global prevalence of roughly 55 million cases in 2021. When couples struggle to conceive, a male factor is involved in about half of all cases, and in roughly 20% of infertile couples, the male partner is the sole cause. These numbers have been climbing steadily for decades, driven by declining sperm counts and a range of lifestyle and environmental factors.
How Male Infertility Fits Into Couple Infertility
Around 15% of couples have difficulty conceiving. For a long time, infertility was treated primarily as a female health issue, but the data tells a different story. Male factor infertility is present in an estimated 50% of couples who can’t conceive. In about 20% of those couples, the problem traces exclusively to the male partner. In the remaining 30%, both partners have contributing factors.
This means that if you and a partner are having trouble getting pregnant, there’s roughly a coin-flip chance that a male factor is part of the equation. Testing both partners early saves time and can prevent months or years of misdirected treatment.
The Most Common Causes
Varicoceles, which are enlarged veins in the scrotum that overheat the testicles and impair sperm production, are the single most common identifiable cause of male infertility. They’re present in about 15% of men in the general population but show up in 40% of men being evaluated for infertility. Among men who previously fathered children but are now struggling (secondary infertility), varicoceles account for up to 70% of cases. The good news is that varicoceles are treatable, and correction often improves sperm quality.
Other well-known causes include hormonal imbalances, blockages in the reproductive tract, testicular injury or undescended testicles, sperm antibodies, and genetic conditions. Among infertile men who undergo a full workup, roughly 40% have no detectable sperm at all, a condition called azoospermia. Another 34% have very low sperm counts. About 5% produce sperm that can’t swim effectively, and a smaller percentage produce sperm with abnormal shape.
Perhaps the most striking finding is how often no clear cause is found. Despite thorough testing, up to 70% of male infertility cases are classified as idiopathic, meaning doctors can identify that something is wrong with the sperm but can’t pinpoint why. This is one reason the condition remains underdiagnosed and undertreated.
Sperm Counts Are Dropping Fast
A landmark meta-analysis published in Human Reproduction Update analyzed sperm samples collected worldwide between 1973 and 2018. The findings were stark: average sperm concentration dropped by 51.6% over that 45-year window. Total sperm count, which accounts for both concentration and semen volume, fell by 62.3%.
What’s more alarming is that the decline is accelerating. From 1973 onward, sperm counts dropped at a rate of about 1.16% per year. But when researchers looked only at data from 2000 onward, the rate of decline had more than doubled to 2.64% per year. This acceleration has raised serious concerns among reproductive health experts, though the exact drivers remain debated. Likely contributors include exposure to endocrine-disrupting chemicals, obesity, heat exposure, pesticides, and sedentary lifestyles.
Where the Problem Is Most Severe
Male infertility isn’t evenly distributed around the world. The highest rates are found in Eastern Europe and Western Sub-Saharan Africa, where prevalence reaches about 1.5 times the global average. Eastern Europe is particularly notable because rates there continue to climb.
Low-income and lower-middle-income regions, including South Asia, Southeast Asia, and Latin America, have seen the steepest increases since 1990. These trends likely reflect a combination of rising environmental exposures, limited access to reproductive healthcare, and higher rates of untreated infections that can damage fertility.
How Age Affects Male Fertility
Unlike the relatively sharp fertility cliff women face in their late 30s and 40s, male fertility declines more gradually, but it does decline. Men older than 40 are about 30% less likely to achieve conception compared to men under 30. Sperm quality, including DNA integrity, tends to deteriorate with age, which can affect not just the chances of conception but also pregnancy outcomes and the health of offspring.
CDC data from 2015 to 2019 shows that among men who have already fathered at least one child, about 12.6% report some form of infertility or impaired fertility. This rate holds remarkably steady across age groups: 11.7% for men ages 25 to 29, rising slightly to 13.3% for men in their early 30s, and hovering around 12.3 to 12.5% for men in their 40s. The consistency suggests that secondary infertility isn’t purely an aging issue. New varicoceles, weight gain, medication changes, or environmental exposures can all emerge after a man has already had children.
What This Means in Practical Terms
If you’re a man wondering about your own fertility, the simplest first step is a semen analysis. It’s noninvasive, relatively inexpensive, and provides a baseline for sperm count, motility, and shape. Because sperm production takes roughly 72 days per cycle, a single poor result doesn’t necessarily mean permanent infertility. Temporary illness, stress, or medication use can all suppress counts temporarily, so retesting after two to three months is standard.
For men diagnosed with low sperm counts or poor sperm quality, treatable causes exist in a meaningful percentage of cases. Varicocele repair, hormone optimization, lifestyle changes (reducing alcohol, managing weight, avoiding excessive heat to the groin), and addressing infections can all improve outcomes. Even in cases where natural conception isn’t possible, assisted reproductive techniques can often work with very low sperm numbers.
The broader trend of declining sperm counts means that male fertility testing is becoming more important, not less. Couples who start investigating both partners early are more likely to find answers quickly and avoid unnecessary delays in treatment.