Written by Melanie Brown. Reviewed by Jenny Wordsworth.

Melanie Brown, BSc (Hons) MSc, has been a nutritionist in the area of fertility and pregnancy for 20 years. She has a master’s degree in Nutritional Medicine, and a special interest in male infertility, endometriosis, PCOS and low ovarian reserve. She covers all aspects of fertility from IVF, advising on diet and lifestyle from pre-conception through to egg collection and embryo transfer, and then beyond to pregnancy. And she is not a hard-core nutritionist; she says, “I love potatoes, wine, croissants and cake, but I think I know how to keep myself in check!” Her own experience of infertility, miscarriage and then early menopause at the age of 42, and her specialised knowledge of how IVF works, drug and nutrient interactions and a genuine empathy with her clients, gives her a unique ability to help her clients achieve their goal of having a baby.

When it comes to male fertility, the most commonly cited metric is sperm count.

It’s easy to understand why - numbers are straightforward, and for decades, semen analysis reports have placed a heavy emphasis on total sperm concentration. But actually, good sperm count is only one piece of a much larger puzzle. 

Evaluating male fertility by sperm count alone is like judging a marathon by how many swimmers show up at the starting line, without watching to see who crosses the finish line. Sperm have a tremendous job to do, swimming the equivalent of the English Channel, navigating obstacles, trying to put off the sperm behind them (yes, they are competitive!) and trying to penetrate the membrane of the oocyte (the egg). This cell is enormous compared to them, and it is extremely fussy about who it will let in. 

If you are trying to conceive, it's time to move past the myth that just having a sperm count equals fertility. Today, reproductive specialists may look at several critical factors beyond count: semen volume, sperm morphology (shape), motility (how sperm moves) and a separate test that looks at DNA integrity. These deeper measurements provide a far more accurate picture of a man's reproductive potential and are essential for diagnosing and treating infertility.

Morphology: Structure Dictates Function

Sperm morphology refers to the size and shape of sperm. The ideal sperm has an oval head and a long tail, which helps it swim efficiently and penetrate the egg’s outer layer. Abnormally shaped sperm - those with large, misshapen heads or coiled, broken tails—may have trouble reaching or fertilising the egg.

The World Health Organization (WHO) considers a morphology rate of just 4% of your sperm to be normally formed or higher, to be within the fertile range, a surprisingly low standard. It means the majority of sperm can be imperfect, but if even a small fraction are structurally sound, fertilisation is possible. Still, poor morphology, known as teratozoospermia, can significantly reduce the odds of natural conception or even hinder assisted reproductive technologies (ART) like IVF.

Motility: The Marathon of Fertility

Sperm motility refers to how well sperm moves. Healthy sperm need to swim vigorously and in a straight line, to navigate the female reproductive tract, which is designed with multiple biological obstacles in order to further filter out the less sound sperm. 

There are two main types of motility:

• Progressive motility: sperm move forward in a straight line or large circles.

• Non-progressive or immotile sperm: sperm that move in one small space or not at all.

Poor motility, called asthenozoospermia, means that there may be lots of sperm present, but they just cannot reach the egg. And while techniques like intrauterine insemination (IUI) and IVF can bypass some of these obstacles, very low motility often requires advanced interventions such as intracytoplasmic sperm injection (ICSI), where a single sperm is injected directly into the egg.

DNA Integrity: The Silent Factor

Perhaps the most overlooked aspect of sperm quality is DNA fragmentation. Even if sperm look healthy and swim well, their genetic cargo (the DNA they deliver to the egg) might be damaged. This is critical because poor DNA integrity has been linked to:

• Lower fertilisation rates

• Higher miscarriage rates

• Poor embryo development

• Failed IVF or ICSI cycles

DNA fragmentation can be caused by a varicocele (a varicose vein in your testicle), oxidative stress, infections, environmental toxins, age, and lifestyle factors such as smoking, recreational drug or alcohol use or poor diet. Sometimes, there is no specific cause identified. Male obesity may also be a risk factor. Unlike sperm count or motility, DNA integrity requires specialised testing, which may be used when couples experience unexplained infertility or repeated IVF failures.

A Holistic View of Male Fertility

It’s important to recognise that sperm health is multifactorial. A man may have a high sperm count but poor motility and morphology. Conversely, someone with a lower count might have excellent motility and DNA integrity, making natural conception entirely possible.

Moreover, the great thing is that male fertility is not fixed. Diet, exercise, sleep, alcohol consumption, and exposure to heat or environmental toxins all influence sperm health. Unlike eggs, which are fixed in number and decline with age, sperm are produced continuously. This means that with targeted lifestyle changes and medical intervention, sperm quality can often be improved within three months, the time it takes for sperm to fully develop.

Why This Matters

Understanding the full picture of sperm health empowers couples to make informed decisions. It can prevent months or years of frustration and unnecessary treatment. Too often, fertility assessments focus on the female partner, while the male factor is only superficially examined. In reality, male factors contribute to infertility in 40-50% of cases.

So next time someone mentions sperm count as the key metric, remember: fertility isn’t just about how many swimmers start the race - it’s about how many finish strong, with the genetic integrity needed to create a healthy embryo.

Final Thoughts

If you’re facing fertility challenges, insist on a comprehensive semen analysis that includes as many semen and sperm parameters as possible, including morphology and motility, and an examination of your testicles. If the sperm test looks ‘OK’ but there is still doubt over the cause of your and your partner’s infertility, ask for a DNA fragmentation test as well. 

Don’t accept “your count looks fine” as the end of the story. Reproductive science has advanced, and your family planning deserves more than a headcount.