When pregnancy does not come, those around you often look first at the woman. Yet in about half of cases the cause lies wholly or partly with the man. In an estimated 1 in 6 to 7 couples trying to conceive it does not happen straight away, and in a good part of those the man plays a part.
To be honest: for many men fertility feels like a sensitive subject, as if it says something about your manhood. It does not. It is biology, and you can often look at it specifically with a semen analysis and some blood values instead of guessing.
How does male fertility work?
Your fertility roughly depends on two things: whether you make enough healthy sperm cells, and whether those can do their work. The making of sperm cells happens in your testicles and takes about three months from start to finish.
That timeframe matters. Something you do now, an illness, a hard period or a lifestyle change, you often only see back months later in your sperm quality. That is why a doctor in doubt looks not at one moment, but at the picture over time.
The control of that whole process runs through your hormones. And that part in particular you can map with a blood test.
Which hormones steer your fertility?
The making of sperm cells and testosterone is regulated from your brain. Your pituitary gland makes two hormones, FSH and LH, that drive your testicles. LH switches on the making of testosterone, FSH stimulates sperm cell production.
That is why a doctor can often read from your hormone values where a problem sits. A high FSH can, for instance, point to a problem in the testicles themselves, while low values point sooner toward the brain. How these hormones connect to your broader men’s health is in our pillar on hormonal health in men.
Which blood values matter for fertility?
With a fertility question a doctor often looks at a set of hormones that together give a picture. None of those values is a diagnosis on its own, but together they tell you where best to look further.
The table below shows which values often play in and why. The exact reference ranges differ per laboratory, so always read the values on your own result form.
| Value | What it measures | Why it matters |
|---|---|---|
| FSH | Hormone that stimulates sperm production | Can point to how well the testicles make sperm |
| LH | Hormone that switches on testosterone production | Helps distinguish where a hormone problem sits |
| Testosterone | Your main male hormone | Low testosterone can go together with lower fertility |
| SHBG | Protein that binds testosterone in your blood | Helps estimate how much testosterone is available |
| Prolactin | Another pituitary hormone | High can disturb the making of sex hormones |
You will also find these values as individual markers: FSH, LH, testosterone and SHBG. How they connect to your sperm quality is in our piece on sperm quality and hormones.
What does a semen analysis say?
The semen analysis, also called a spermogram, is the main test in male fertility. Here a laboratory looks at the number of sperm cells, how well they move and how they are shaped. Together those give a picture of your sperm quality.
Because sperm quality can differ from day to day, an abnormal result is usually repeated. So one poorer result does not automatically mean a problem. How to read the values of a semen analysis is in our separate piece on semen analysis values.
Common causes in men
The causes of lower fertility in men are diverse, and often it is a combination. Sometimes it is the sperm production, sometimes the transport, sometimes hormones. In a part of cases no clear cause is found.
Known factors are a varicose vein in the scrotum, earlier inflammations or operations, certain medicines, and lifestyle. Heat plays a role too, because your testicles work best just below body temperature. According to Thuisarts.nl, in a part of men no identifiable cause can be found, and that can be frustrating.
That finding no cause is not the same as no chance is important to remember. Many couples still conceive, with or without help.
Fertility, testosterone and TRT
This is the part that surprises many men, and is exactly important. Testosterone as a medicine, for instance via a testosterone course or TRT, does not improve your fertility. In fact, it can strongly suppress the making of sperm cells.
That is because external testosterone slows the signal from your brain, the FSH and LH. Your testicles then get less stimulus to make sperm. For a man who wants children, that is a crucial detail rarely told in the gym.
If you have a low testosterone and a wish for children, discuss that with a doctor before starting a course. There are other routes that can support your hormones without undermining your fertility. What TRT otherwise does to your values is in our piece on blood values before you start TRT.
What can you do yourself for your fertility?
Lifestyle makes a difference, though it is rarely a miracle cure. Because the making of sperm cells takes about three months, changes need time before you see them back. So patience is part of it.
The familiar basics count: not smoking, going easy on alcohol, a healthy weight and enough movement. Too much heat around your testicles, such as frequent sauna or a laptop on your lap, is better limited. According to the RIVM and GP guidelines, smoking and overweight are among the factors that can unfavourably affect your sperm quality.
Also be careful with anabolics and unknown performance agents, because those can seriously undermine your fertility. None of these steps is a guarantee, but together they give your body the best starting position.
Age and male fertility
Men make sperm cells throughout their lives, unlike women. Still, age is not entirely neutral: on average sperm quality declines somewhat over the years, and the time needed to conceive rises.
The effect is usually gradual and less pronounced than in women. But if you and your partner are both somewhat older, that can together weigh in. It is a reason, with a pregnancy that does not come, not to keep waiting endlessly.
A varicose vein in the scrotum: a common cause
A varicocele, a varicose vein in the scrotum, is one of the best-known physical causes of lower sperm quality in men. It is a widened vein that can create extra heat around the testicle, and heat in particular is unfavourable for sperm production.
Not every varicocele gives problems, and many men with one simply have children. But with a pregnancy that does not come, it is something a doctor can check. Sometimes something can be done about it, sometimes waiting is wiser.
The point is that you rarely notice this yourself. That is why a physical examination of the man, besides the semen analysis and the hormones, belongs to a complete picture.
What happens in a fertility examination of the man?
A fertility examination of the man usually starts simply. The GP or a specialist discusses your history, your lifestyle and your symptoms, and requests a semen analysis. That is often the first and most important step.
Depending on the result, a blood test for your hormones can be added, and sometimes a physical examination or a scan of the scrotum. That way a doctor builds a picture step by step, without doing everything at once.
Important: this examination is not there to point a finger, but to understand where the chance lies to improve something. For many couples that leads to a targeted plan.
Myths about male fertility
Around male fertility there are many stubborn stories. Tight underwear or a laptop on your lap is often named, but the evidence for that is weak. Extreme and prolonged heat can play in, but a warm pair of trousers once is no disaster.
Another misunderstanding is that fertility is the same as potency. A good erection says nothing about your sperm quality, and the other way around. They are two separate systems that you can assess independently of each other.
And the idea that it is always down to the woman simply is not true. In about half of cases the man plays a part, and that is exactly why testing both partners is useful.
When should you get tested?
A common rule of thumb is to get tested if pregnancy does not come after about a year of regular, unprotected sex. If there are reasons to look earlier, for instance earlier problems or a higher age, that can be sooner.
In the man that testing usually starts with a semen analysis, possibly with hormone measurements in your blood. What the man can have tested exactly is in our piece on trying to conceive does not work. Always discuss an abnormal result with a doctor, because a single measurement is a snapshot.
What a blood test can tell you
A blood test can map the hormones that steer your fertility, such as FSH, LH and testosterone. That says something about the hormonal side, but does not replace a semen analysis, which assesses the sperm cells themselves. Together they give the most insight.
The IVF Partner Screening is aimed at the man in a conception journey, and the Hormones Man panel maps your broader male hormones. The explanation and follow-up belong with your doctor.
See such a test mainly as a starting point that you can use together with your partner and your doctor to make targeted choices, not as a final verdict on your chances.
Frequently asked questions about male fertility
Does my testosterone say something about my fertility?
Partly. A very low testosterone can go together with lower fertility, but a normal testosterone does not guarantee good sperm quality. That is why a doctor, besides testosterone, also looks at FSH, LH and especially a semen analysis. The whole picture counts, not one value.
Does a testosterone course improve my fertility?
No, usually the opposite. Testosterone as a medicine slows the signal from your brain and can suppress the making of sperm cells. If you want children, discuss with a doctor which approach supports your hormones without harming your fertility.
Can I improve my sperm quality myself?
Sometimes partly, via lifestyle: not smoking, going easy on alcohol, a healthy weight and not too much heat around your testicles. Because sperm cells need about three months, you only see effect later. It is an addition, not a guarantee, and in doubt a doctor belongs in the picture.
How long before lifestyle improves my sperm quality?
Count on at least two to three months, because that is how long the ripening of new sperm cells takes. If you stop smoking or lose weight, you only see any effect back after a number of months in a new semen analysis. Patience and a repeat measurement are part of it, so keep up changes instead of judging after a few weeks.
Sources
- NHG (Dutch College of General Practitioners). NHG guideline Subfertility.
- Thuisarts.nl. We would like to get pregnant.
- RIVM (National Institute for Public Health and the Environment). Lifestyle and fertility.
Disclaimer
Caliberhealth works with BIG-registered doctors who review your blood results. This article provides general information and is not a substitute for medical advice from a GP or specialist. A blood test is a tool, not a diagnosis in itself. For serious or persistent symptoms, contact your GP, or call 112 in an emergency.
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