| Published: September 29, 2025 Last reviewed: October 9, 2025 |
While many are aware that female fertility declines with age, fewer people realise that the effect of age on sperm quality can be significant as well. As men age, changes in the quality of sperm can drastically impact the chances of conception, even in fertility treatments like IVF. These subtle yet important shifts in reproductive health may lower success rates or increase the time it takes to achieve pregnancy. The good news is, there are proactive steps you can take to support and improve sperm health.
What is sperm quality & how is it measured?
Sperm quality refers to how healthy and capable a man’s sperm are when it comes to achieving pregnancy. While many people think only sperm count matters, there are several key factors that determine overall sperm viability. These include: sperm count, motility, morphology, volume and pH, and vitality. All these elements are measured through a semen analysis, a simple laboratory test.
The factors of sperm quality
Sperm count
Sperm count is measured by a technician using a special counting chamber to determine how many sperm cells are present in a defined volume. Results are expressed as sperm concentration (sperm per millilitre) and total sperm per ejaculate. According to WHO, normal concentration is higher than or equal to 15 million sperm/mL, while a normal total count is higher than or equal to 39 million per ejaculate. Low sperm counts may signal hormonal imbalances, genetic issues, varicocele, or lifestyle-related factors.
Sperm motility
Sperm motility (movement) is typically classified into three categories: motile, non-progressively mobile, or immotile. Motile sperm actively and purposefully move in a straight line or large circles. They are considered the most capable of reaching the egg. Non-progressive mobile sperm move, but not in a straight line or with little forward progression. They might move in small circles, twitch, or show tail movement without covering much distance. Immotile semen shows no movement at all and can notably lower fertility potential.
Sperm morphology
Sperm morphology refers to the shape and structure of sperm, providing insight into how many sperm cells are normally formed versus abnormally shaped. A skilled technician examines at least 200 sperm and classifies each one based on the shape of the head, midpiece, and tail. It is reported as a percentage of sperm that are normal in shape. According to strict Kruger criteria, the normal range is 4% or higher. Poor morphology prevents the sperm from swimming properly, penetrating the egg, and fertilising it successfully.
PH level
The pH level determines the acidity or alkalinity of the semen, which plays a crucial role in sperm function and overall male fertility. The pH is tested within an hour of sample collection by dipping a strip into the semen, which is then compared to a colour chart. A healthy pH level is slightly alkaline, protecting sperm from the acidity of the vaginal environment. Abnormal pH levels can impair sperm motility, reduce fertilisation potential, and indicate underlying medical issues.
DNA integrity
The DNA integrity of sperm is analysed through specialised tests that assess the quality and stability of the genetic material carried within the sperm. Even if sperm look healthy under the microscope, they may carry fragmented or damaged DNA, which can lead to lower fertilisation rates, higher risk of miscarriage, poor embryo development, and delayed or failed pregnancy.
Does sperm quality affect IVF success?
Sperm quality can seriously affect IVF success, even when assisted reproductive techniques like ICSI are used. While IVF is often associated with female fertility, it’s especially sperm health that plays a vital role in embryo development, implantation, and pregnancy outcomes. That’s why sperm donors undergo strict screening to increase success rates.
Does sperm quality decline with age?
Yes, although more gradually than female fertility, the effect of age on sperm quality is real. Advanced paternal age, typically above 40-45 years, is linked to a decline in sperm function, an increased risk of fertility and offspring health, and decreased chances of fertilisation.
Unique sperm factors that diminish as men age include:
- Sperm count: fewer sperm per ejaculate
- Motility: less mobile sperm
- Morphology: lower percentage of normally shaped sperm
- DNA fragmentation: an increase in damage leading to lower quality embryos, poor implantation, and a higher risk of miscarriage
At what age does sperm quality start to decline
Male sperm quality declines from around age 40–45, though this varies per individual. As men age, sperm motility decreases due to oxidative stress, structural damage to the tail, and declining testosterone levels. These changes result in fewer sperm that can swim efficiently toward the egg. Some sperm may develop bent or broken tails, reducing their ability to fertilise an oocyte.
Studies show progressive motility can decline by up to 1% each year. Older men also tend to have a higher percentage of immobile sperm, which can drastically impact the chances of natural conception, IUI, or IVF success.
How does sperm quality affect IVF success rates
Semen quality is crucial to IVF success, as it directly influences the ability to achieve conception and develop a healthy embryo. Key factors include sperm count, motility, morphology, and DNA integrity. For instance, low motility and morphology can reduce the sperm’s ability to reach and penetrate the egg, especially during conventional IVF. Low sperm count reduces the overall number of viable candidates, while DNA fragmentation may affect embryo development even if fertilisation occurs. Understanding these factors helps fertility specialists recommend the most effective treatment to maximise success.
How to improve sperm quality at any age
At any age, sperm quality can be improved with easy changes in lifestyle and diet. Making these adjustments early can positively influence fertility and boost successful chances:
- Eat a healthy diet rich in antioxidants, vitamins (especially C, D, and E), zinc, and folate; include leafy greens, berries, nuts, whole grains, and lean proteins.
- Exercise regularly, but avoid overtraining.
- Avoid smoking, limit alcohol, and stay clear of illicit drugs and certain medications that harm sperm production.
- Minimise heat exposure, like hot tubs, saunas, or tight underwear.
- Reduce stress through meditation, adequate sleep, and counselling.
- Limit exposure to toxin's including pesticides, industrial solvents, or heavy metals.
- Maintain a healthy weight and stay well hydrated.
Genea Fertility’s approach to donor sperm
At Genea Fertility, we take a careful and considerate approach to collecting donor sperm. Each sperm donation undergoes strict screening, including comprehensive medical, genetic, and psychological tests. This rigorous process assures that hereditary conditions, STIs, and other infectious diseases cannot be transmitted to the recipient and future child. Donor sperm is also meticulously screened for high quality to maximise the chance of conceiving.
We understand that it can be overwhelming to get started on your fertility journey. To set your mind at ease and find out clear next steps, connect with our Fertility Concierge today.
Disclaimer: Please note that this is a Genea Group blog and as such information may not be relevant for all clinics. We advise that you consult clinics directly for further information.
