The testicle is a high-powered machine that typically cranks out over 1,000 sperm per second. Sometimes, the machinery can get gummed up, slowing down sperm production.. This article explores in-depth how sperm production is measured, what causes a low sperm count, how many sperm it takes to make a baby and what men can do to improve sperm production.
How sperm count is reported on lab results
Lab reports will often report two separate numbers for sperm count. The first is sperm concentration (sometimes called sperm count) and the second is total sperm count. What’s the difference? Sperm concentration is is the number of sperm in each milliliter of semen and the headline result that most people refer to when discussing male fertility, total sperm count refers to the total number of sperm in the entire sample. The amount of semen impacts the total number of sperm cells available in the sample. Calculate total count by multiplying the concentration by the volume. The table below shows a couple of examples:
|Sperm Concentration||Semen Volume||Total Sperm Count|
|10 Million per mL||2 mL||20 Million|
|10 Million per mL||5 mL||50 Million|
Semen volume is an important parameter to consider when evaluating sperm count. Alone, a sperm concentration of 10M per mL would be considered a “low” sperm count. But if accompanied with a high semen volume, the total sperm count is may not be that low.
How labs measure sperm count
To understand the challenges associated with semen analysis, imagine a 10,000 gallon pool full of thousands goldfish and you wanted to count them. How would you do it? You could stand there and try to count them all. But they are swimming so it’s difficult to keep track of which fish you already counted. You could reach in and scoop out a gallon jug full, count the fish in the jug and then multiply by 10,000 to estimate the total number. What if you scoop out a jug with water but no fish? Obviously there are fish in the pool. What if the jug has too many fish and they are moving too fast to count them?
The most widely accepted method for counting sperm is to view a small fraction of a semen sample under a microscope and counting the sperm cells. Special microscope slides called hemocytometers contain a visual grid to make it easier for a technician to count the cells. The grids are cleverly designed to make math simple so a technician can easily calculate how many million cells are in the sample based on how many sperm are in each square and how many squares the technician counts.
Some labs have computer-aided semen analysis (CASA) machines that take a video of sperm cell swimming under the microscope and use analysis software to automatically count and characterize sperm. Various other technologies have been invented to measure sperm count, but no test is perfect. Depending on the method, the technology used, and the skill of the technician there are many sources of error that can occur. The most major sources of error include:
Counting error: Counting errors happen when sperm are moving too much, there are too many cells to easily count, or the technician doesn’t count enough squares to accurately estimate the true sperm count. One way to reduce this error is to de-activate, or “fix”, sperm so they can’t swim, making them easier to count. Increasing the number of grid squares or number of cells counted can also improve accuracy.
Sampling error: Going back to the swimming pool metaphor, imagine all the fish go to the bottom and you take a bucketful from the top. This would not be a good estimation of the true count. Similarly, sperm tend to hang out in clumps due to the viscosity and structure of semen. It is possible for a technician to draw a sample that has an abnormally high or low concentration of sperm. To overcome this challenge, some labs will require extensive sample mixing, or “homogenization”, to even out the distribution. They may also require technicians to draw and count multiple samples from the semen specimen to ensure that the counts are equivalent from sample to sample.
Performing a rigorous semen analysis can be both labor intensive and expensive. Most labs will do an initial analysis with a more relaxed protocol to save time and money. If the results come back low, then some will take additional efforts to ensure accuracy. It is important to recognize that semen analysis – even when performed under careful and well-controlled conditions – can have error of up to 20%. This means that if your sperm count is measured 10 million cells per mL (M/mL), it could really be anywhere from 8 – 12 M/mL. So you need to think of it more as a range rather than an absolute measurement.
Daily Variations in Sperm Count
A man’s sperm count varies greatly from day to day and week to week. In the short run, much of the variability is due to sample collection and handling. In the longer term, variations can be much larger and can be caused by a number of biological and physical events that impact sperm production – such as having a fever, taking a new medication, or changes in diet.
Variations due to sample collection & handling
If you are interested in seeing trends in sperm count over time, you will want to try to be consistent in the way you collect and handle the semen sample for each semen analysis. Here are the major causes of variation due to sample collection & handling.
Collecting a sample: There are three important factors during sample collection that can impact test results – abstinence period prior to sample collection, excitement level during collection and how much of the sample gets collected.
Abstinence: Abstinence greatly impacts sperm count. Sperm stores are depleted with each ejaculation and take about 2 days to refill. As abstinence period increases, sperm slowly build up. If abstinence is greater than 7 days, sperm begin to die and decompose causing the semen sample to be filled with excess cell fragments and other debris. For this reason the WHO recommends an abstinence period of 2 -7 days. When having a repeat semen analysis performed, you can optimize precision by abstaining for the same amount of time for each test.
Method of Collection: Your body can tell when it is “the real deal.” The more excited you are during collection, the more sperm are found in the ejaculate. Some studies have found that samples collected at home where the man is more comfortable have had higher values for sperm concentration, total count and motility. Excitement level during collection is obviously difficult to control but it does contribute to variation of semen analysis results and may be worth taking a mental note.
Collecting the Sample: Just be sure the entire sample makes it into the cup. The first few drops of the ejaculate contain the majority of the sperm cells, so missing the first drops can cause lower results. Likewise, the latter part of the ejaculate consists primarily of seminal fluid so if that part is not collected, the result can show up as artificially high.
Handling samples after they’ve been collected: When initially collected, semen can be very viscous and technicians may need to wait several minutes before analyzing the sample (the sample will become less viscous over time). However, as a sample sits in the cup cells quickly begin to die and deteriorate. If the sample is not analyzed shortly after collection, sperm motility data (the percentage of sperm cells that swim) drops dramatically and sperm count can decrease as cells break apart.
Because technicians need to know how much time has elapsed from collection until running the analysis, clinics prefer on-site collection. The fresher the sample, the more accurate the results will be. If collection on-site is not possible, it is important to be fastidious about the time of collection. Recording time of collection will help technicians ensure that the sample is processed in an appropriate amount of time.
Variations in sperm count due to lifestyle
Over the longer run, lifestyle or specific life events can cause spikes and dips in sperm count. Some of the biggest culprits include fever or heat exposure, diet, exercise, stress level, toxin exposure and BMI. There are even a number of studies that show sperm counts vary from season to season, probably due to temperature changes. How much can these things impact sperm count? Quite a bit.
This is a chart from the World Health Organization’s manual on laboratory semen analysis. demonstrating the variability in sperm count and sperm concentration in 5 men over the course of a year and a half.
What’s a Normal Sperm Count?
To calculate the average sperm count in men, researchers have conducted large studies of over 1,000 men in a defined geographic region. Some studies further refine the study and recruit certain subgroups of men such as infertile men or recent fathers. Studies found the range of sperm concentrations to be anywhere from 0 to 250 million sperm per milliliter with an average of 60 – 80 million sperm per milliliter. The following graph from a study done in 2012 illustrates the breakdown of sperm counts among young men in Denmark.
The World Health Organization analyzed global data from over 2,000 recent fathers to define semen parameters for fertile men. In this study, the median sperm concentration (50th percentile) was found to be 73 M/ml. They also defined the 5th percentile to be the cut-off for a “normal” sperm concentration, which came out to be 15 M/ml. In other words, 95% of fertile men have a sperm concentration above 15 M/mL. Sperm concentration below the cut-off of 15M/ml does not mean infertility (as the study was done with recent fathers) but it does mean a man falls in the bottom 5% of the normal range.
Global Decline in Sperm Count
Because “normal” sperm counts are defined by gathering data from a large number of men, studies are done periodically to examine differences in semen quality from one country to another, from season to season and decade to decade. These studies help scientists identify trends.
Scientists are usually very careful about not drawing conclusions too quickly, so if you talk to a number of andrologists (scientists who study sperm) you would get a number of very long, nuanced answers, but there are a number of large studies that show sperm counts may be declining worldwide.
Infertility rates have increased the past few decades. Some of this is caused by the trend in developed countries to delay childbearing to later in life, and many experts have begun campaigns to raise education and awareness about the decline in female fertility that begins as early as age 30. As a result more and more women are being proactive to protect future fertility by freezing eggs. However, less publicized is the fact that men contribute to 50% of infertility cases. The global decline in sperm counts is also contributing to the rise in infertility rates worldwide. Sedentary lifestyle, poor diet, increased obesity and toxin exposures are some of the leading suspected offenders currently being studied by researchers.
How many sperm does it take to get pregnant?
The simple, but important answer is 1. So, why do men make so many sperm? From the time a sperm is made, it is constantly in danger of being destroyed. Inside the man’s epididymis, reactive oxygen species attack sperm cells. Once ejaculated in the vaginal tract, sperm are attacked by acidic vaginal fluids and white blood cells. Finding the fallopian tube is like finding a needle in a haystack. Most sperm get lost. Of the millions of sperm released upon ejaculation, only 10-30 make it to the fallopian tube where the egg is released. There, the sperm must survive long enough to meet and fertilize the egg.
Many factors influence a couple’s monthly chance of conception – the woman’s age, the “friendliness” or “hostility” of her vaginal tract, the quality of the semen that transports the sperm and the health of the sperm cells. When optimized, all these factors combined add up to something in the range of a 30-35% chance of conception. As factors become less optimal, the monthly chance of conception goes down to zero.
Sperm count is a factor that impacts the monthly chance of conception. However, it is very hard to precisely correlate sperm count to chances of pregnancy. A man that has a low sperm count with healthy sperm may have a better monthly chance of conceiving than a man who has a higher sperm count but the sperm are unhealthy. Several large scale studies have analyzed the relationship between semen quality and how long it took a couple to get pregnant. One study found that men with healthier sperm had a shorter time to conception. Another study found that the more sperm a man had (up to around 55M/ml) the better his chances of conception.
As sperm concentrations drop below 10 M/ml, odds of natural conception get pretty dicey and most reproductive endocrinologists will recommend some sort of assisted reproduction treatment. Sperm concentrations in the range of 1-10M/ml often have success with cervical cap or intrauterine insemination if there are no female factors present. When the sperm concentration is lower than 1M/ml, doctors will often recommend an in-vitro fertilization procedure called intra-cytoplasmic sperm injection (ICSI) for the highest chances of success. ICSI involves isolating a single sperm cell and carefully injecting it into the woman’s egg.
Causes of Low Sperm Count
Sperm count is not a static number like your height or your shoe size. It is a dynamic indicator of testicular health. Like other aspects of health – blood pressure, cholesterol or blood sugar levels – event shocks like high stress and fever can cause dips in sperm count. Long-term unhealthy lifestyle such as poor diet, smoking and a beer belly can also significantly suppress sperm production.
There are also medical reasons for a low sperm count in otherwise healthy men including the presence of a varicocele (varicose veins in the scrotum), past illnesses or infections, maldescent of testicles during childhood, prior surgeries in the groin (such as hernia repair), hormone imbalances and genetic disorders. Fill out our complete Risk Assessment to get a comprehensive assessment of risk factors that could be impacting your fertility.
Lifestyle: We like to use the acronym SHOT — Stress, Heat, Obesity, Toxins — as a quick way to remember the major lifestyle contributors to low sperm count. Studies have shown these factors can reduce sperm counts all the way to zero in extreme cases.
Varicocele: Varicose veins in the scrotum, known as varicoceles, have been known to impact testosterone and sperm production as well as sperm health (motility, morphology). Varicoceles are relatively common, occurring in about 15% of all men, and impact men differently. Some men can have large varicoceles with little to no impact on fertility, while other men are more sensitive and even small varicoceles can dramatically impact semen parameters. Varicoceles are repairable through surgery; it often takes 6-12 months post-surgery to fully improve fertility.
Genetics: There are a number of genetic disorders that contribute to male infertility. Because the molecular science is still relatively young, new genetic markers for male fertility are still being discovered. The good news is that most genetic causes of infertility are relatively rare. The most common disorders are:
Klinefelter’s Syndrome: Genetic condition in which a man has an extra X chromosome causing him to be XXY rather than the normal XY.
Y chromosome microdeletions: The deletions of genes from the Y chromosome that are responsible for sperm production.
Infection: Viral and bacterial infections – both in childhood and as an adult – can cause scarring on tiny microtubes of the male reproductive tract leading to a partial or complete blockage. Leading offenders include: mumps, tuberculosis, chlamydia, gonorrhea, mycoplasma, urinary tract infections and prostate infections.
Hormone imbalances: Hormones play a critical role in the production and maturation of sperm cells. For reproductive health, the most critical hormones include – Testosterone, Follicle Stimulating Hormone (FSH), and Luteinizing Hormone (LH). Hormonal imbalances can occur for a number of reasons including: impaired testicular function, thyroid disorders, diabetes, pituitary disorders or growths and abuse of androgens for athletic performance.
Tips for Boosting Sperm Count
Even in circumstances in which sperm production is suppressed by a medical condition such as a varicocele or hormone imbalances, lifestyle changes targeted to improve sperm production can dramatically improve sperm count, motility and morphology. It is important to recognize that start to finish it takes about 72 days to make a sperm, so things that you implement today will take a few months to really take effect. Here are some of the top tips:
2. Watch what you eat
3. Lose weight
4. Pay attention to sources of heat
5. Ice your balls
6. Lift weights
7. Go for a run
8. If you have a desk job, take breaks and walk around
9. Don’t do drugs — this includes mary jane
10. Read up on your meds – some medications can interfere with sperm production
11. Don’t juice (not talking about raw foods here)
12. Limit alcohol
13. Don’t wear tight clothes too many days in a row
14. Meditate, take a run or find some other healthy outlet for stress
15. Have lots of sex (but lay off the lube)
16. Play team sports
17. Don’t watch TV for longer than 1 hour at a time
18. Be careful if biking
19. Take a multivitamin
20. Try acupuncture
Getting Pregnant with a Low Sperm Count
Fertility is a team sport. To understand the best path to pregnancy, you need to consider what’s happening with each partner and if there are any compatibility issues. Sometimes there are very clear issues that can be identified and treated by doctors. Other times, infertility can stem from multiple factors or be unexplained which is damn frustrating. Patience, communication and education can go a long way in helping you figure out the best path forward.
From cheap and non-invasive to expensive and invasive, here are some tools for improving your odds of trying to conceive if your swim team is a little low. Note: taking steps above to improve sperm count will improve your chances of conception even if you decide to pursue IVF or ICSI.
Creating a Sperm Friendly Environment: There are a number of over the counter products available to improve the sperm-friendliness of the female reproductive tract including pre-seed, Astroglide TTC and GoBaby pH.
At-home assisted reproduction: Cervical cap insemination is a technique that has been used by OB-Gyns for decades to increase odds that sperm will make it to the egg. In this technique, sperm are collected into a container that is placed directly on the cervix. This shortens the distance sperm have to swim and reduces the obstacles along the journey. Modern technology makes it possible to bring this proven medical technique into the home. Cervical cap insemination is recommended when total motile sperm count is above 1 million
Intrauterine insemination (IUI): Commonly called IUI, intrauterine insemination is commonly practiced by many OB-Gyns and fertility clinics as a low cost procedure to improve chances of conception when the male partner has a low sperm count. It is recommended when total motile sperm count is above 1 million. The procedure involves producing a semen sample on-site. Healthy sperm cells are “washed” or removed from semen and placed in a nutrient rich solution which is placed into a “straw” and inserted directly into the uterus.
Intra-cytoplasmic sperm injection (ICSI): This is the highest-tech baby-making option. The procedure on the female side is identical to a normal IVF cycle. Medications are administered to hyper-stimulate ovaries and mature eggs are harvested. The semen sample is “washed” and then placed on a special microscope. A single sperm cell is selected and the tail is cut off by a technician. It is then sucked up into a tiny needle and injected directly into the egg which is held in place by a specialized micro-pipette. The process is repeated for each egg harvested. Resulting embyros are then monitored and the top 1 or 2 are selected for implantation. The rest are frozen for future use.
This doesn't need to be a taboo subject left in a closet, nor do men need to go through this alone. Education and community are key elements to improving health. Don't cook your balls is a space for us to share science and experience advance the state of male reproductive health care.
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