10 Things That Impact Sperm Quality
Even though so much of the fertility conversation centers around eggs, 40% of infertility is either solely caused by or contributed to by a male factor. So when someone says, “Don’t evaluate him, the problem is me,” that’s simply not true. We don’t know what we don’t know, and the semen analysis is a critical part of the evaluation.
Let’s quickly review what a semen analysis tells us. We’re looking at:
How many sperm are there? (count)
How do they move? (motility)
What do they look like? (morphology)
This gives us a general sense of sperm production, but it doesn’t tell us everything about functionality. What we do know is that certain lifestyle factors can dramatically impact sperm, and because sperm are constantly being regenerated, you can actually improve them.
A sperm’s life cycle is about 90 days: ~72 days of development and ~18 days traveling from the testes into the ejaculate. That means if you make changes now, you can see different sperm three months from today.
So let’s break down the top 10 things that negatively impact male fertility — and that you can change.
1. Smoking Cigarettes
Smoking creates significant oxidative stress, which damages DNA, decreases motility, and worsens morphology. It affects both eggs and sperm, but sperm are especially vulnerable.
If you’re trying to conceive, smoking has to go.
2. Alcohol
You may hear, “My friend drinks all the time and has five kids.” Sure — but we’re talking about optimizing fertility, not anecdotes.
Alcohol:
lowers sperm count
decreases motility
worsens morphology
increases DNA fragmentation
There is no known “safe amount,” but minimal intake is defined as fewer than four drinks per week — and yes, real-sized drinks, not Texas-sized pours.
3. Marijuana
Research here is limited because of prior legality issues, but what we do have is compelling:
decreased sperm concentration
decreased morphology
reduced testicular volume
impaired hormone production
Studies on primates show severe reductions in sperm production with edible forms as well. And the good news: many parameters improve within four months of stopping.
Daily or chronic cannabis use can significantly harm sperm quality — even when a semen analysis appears normal.
4. Environmental Toxins (Including Heat)
This includes plastics (like BPA), chemicals, pesticides, and industrial toxins — all linked to impaired sperm production.
But heat deserves its own moment:
long cycling sessions
hot tubs and saunas
laptops directly on the lap
The testes live outside the body for a reason: they require cooler temperatures. Significant heat exposure can decrease sperm production.
5. Obesity
Fat tissue produces estrogen, which suppresses the brain’s ability to send FSH and LH — the hormones responsible for sperm production. Obesity also creates chronic inflammation and oxidative stress.
Losing weight when overweight or obese can lead to meaningful improvements in sperm parameters.
6. Poor Diet
Processed foods and high-sugar diets consistently correlate with worse sperm quality.
What hurts sperm:
processed meats (bacon, hot dogs, sausages)
organ meats (yes, the “eat liver to boost fertility” trend is incorrect)
high-sugar, low-nutrient diets
What helps:
Mediterranean-style eating
fish and shellfish
fruits and vegetables
whole foods and healthy fats
Diet matters — a lot.
7. Viral Illness or Major Illness
Severe illness or high fever can temporarily stop sperm production. Classic examples include mumps, which can cause permanent testicular failure. COVID is associated with temporary drops in sperm count, typically recovering after ~3 months.
Acute illness is stressful for the body — and sperm production is deprioritized.
Chronic stress, similarly, disrupts the brain’s hormonal signaling and reduces sperm output.
8. Age
Male fertility isn't immune to aging.
With advanced paternal age (typically >50), we see:
reduced sperm production
increased miscarriage risk
higher rates of neurodevelopmental disorders, including autism spectrum disorders
Age matters for men too — just differently.
9. Medical Conditions
Uncontrolled medical issues can impair sperm production. The biggest culprits:
Diabetes
untreated depression or anxiety
chronic inflammatory diseases
autoimmune conditions
When well-managed, these conditions have less impact. But when uncontrolled, they reduce the body’s energy and resources needed to generate healthy sperm.
10. Testosterone or Steroid Use
This is a big one — and one of the most misunderstood.
Testosterone therapy or anabolic steroids shut down sperm production. Completely.
Many men are prescribed testosterone for fatigue or low libido without any counseling about fertility implications. But:
Taking testosterone = male birth control.
Even after stopping, sperm often take months to return — and sometimes do not recover fully.
If someone with sperm is trying to conceive, they need to avoid testosterone unless it’s being managed by a fertility specialist. Treatments like Clomid, hCG, and aromatase inhibitors stimulate natural testosterone production without shutting down sperm.
