A study in Andrology found that sperm DNA fragmentation tended to increase with age. Measures of abdominal fat also drew attention, but some associations lost statistical significance once other factors were considered.
Sperm count, movement and the proportion with normal morphology are familiar measures of semen quality. Researchers are also interested in the DNA fragmentation index (DFI), a measure of damage to the genetic material sperm carry. Could damage be related to a man's weight? Could two men who weigh the same differ according to where they carry their fat?
A study published August 27, 2026, examined male age, obesity-related body measurements and sperm DNA fragmentation. The researchers observed a trend toward higher DFI with age. Their results suggest that abdominal fat and metabolic health deserve consideration, although they could not establish abdominal obesity as a direct cause of DNA damage.
Normal sperm counts can coexist with DNA damage
Sperm deliver paternal genetic information to the egg. DNA is packed tightly into the sperm head, and breaks in this material are known as DNA fragmentation. DFI is the proportion of sperm showing such damage. It can be elevated even when count and motility appear normal.
Researchers are interested in whether fragmentation relates to embryo development and pregnancy outcomes. Different assays have different thresholds. An elevated result does not establish that natural conception is impossible or that IVF will fail.
The location of fat may matter alongside body weight
Body mass index (BMI) divides weight by height squared and is widely used to assess obesity. It does not distinguish muscle from fat or identify where fat is distributed. Two men with identical height and weight can have the same BMI despite very different proportions of muscle and abdominal fat, and potentially different metabolic health.
Visceral fat is associated with insulin resistance, chronic low-grade inflammation and altered lipid metabolism. Researchers are studying how that environment might affect sperm production and function. Measures of fat distribution might therefore add context to weight or BMI. This study did not establish waist circumference as a more accurate predictor of DNA damage than BMI.
DNA fragmentation tended to rise with age
Men can continue making sperm into older age, but the genetic quality of sperm may change over time. Changes in oxidative stress during sperm production or in cellular repair capacity are possible explanations for the observed association. Individual health, lifestyle and underlying disease vary considerably, and age alone cannot identify which men have substantial sperm DNA damage.
What happened after researchers accounted for other factors?
Some associations between measures of abdominal obesity and fragmentation did not persist in subgroup analyses or after adjustment. Age or other health factors may partly explain the original findings. Smoking, alcohol use, inadequate sleep, metabolic disorders and varicocele are also relevant considerations. A waist measurement alone cannot diagnose sperm DNA damage.
What this means before conception
For men planning pregnancy, semen measurements form part of a broader health assessment. Exercise, a balanced diet and adequate sleep can support metabolic health. Reducing waist circumference does not guarantee a fall in DFI or a greater chance of pregnancy.
DFI testing is not routinely recommended for every man. The clinical circumstances, including repeated pregnancy failure or miscarriage, can guide a discussion with a reproductive specialist about whether testing would help. Understanding male fertility requires looking at the genetic material sperm carry and the environment in which they develop, alongside count and motility. Age, abdominal fat and metabolic health tell different parts of that story.
Source: Andrology, August 27, 2026. DOI: 10.1111/andr.70354. PMID: 42658106. The study reported statistical associations. Individual decisions about testing and treatment should be discussed with a reproductive medicine specialist. The accompanying illustration depicts a fictional person.
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