A couple goes through IVF. The embryos look good on paper, the transfer goes smoothly, and then the cycle fails. It happens again in the next round. Most of the testing so far has focused on the woman, and the man’s basic semen report came back normal. This is one of the more frustrating patterns in fertility care, and sperm DNA fragmentation is one reason it can happen. A standard semen analysis checks how sperm look and move. It does not look inside them, at the genetic material an embryo depends on.
Male Infertility and IVF
Male factor plays a part in roughly half of all infertility cases. Even so, it often gets less attention than the female side during an IVF workup. A routine semen analysis measures three things: count, movement, and shape. All three can sit in the normal range while the DNA packed inside the sperm is damaged. That gap is why some couples reach repeated IVF failure without a clear reason in the reports in front of them.
How Sperm DNA Damage Affects Fertility
Every sperm carries a tightly wound set of DNA. At fertilisation, that DNA joins the egg’s and becomes the blueprint for the embryo. Sperm DNA fragmentation means breaks have formed in that genetic material. Most of the damage traces back to oxidative stress, when harmful molecules in the body outpace the defences that neutralise them.
An egg can repair a certain amount of this damage on its own. A younger, healthier egg repairs more. Past that limit, the damage begins to tell. Fertilisation may still happen, but the embryo can develop poorly, stall, or fail to implant.
Causes of Repeated IVF Failure
Repeated IVF failure rarely comes down to one thing. Several factors can be involved, sometimes together:
- Egg quality, which declines with age
- Chromosomal problems in the embryo
- The receptivity of the uterine lining
- Sperm quality, including DNA damag
Sperm DNA Fragmentation and IVF Success
Research links high sperm DNA fragmentation to lower fertilisation rates, poorer embryo quality, weaker implantation, and a higher risk of miscarriage. It also turns up more often in couples dealing with recurrent pregnancy loss and repeated implantation failure.
The evidence is not absolute, and it is worth being honest about that. The tests measure the damage, but they cannot perfectly predict who will conceive, and a high result does not rule out a healthy pregnancy. What the research does support is treating raised fragmentation as a real factor worth addressing, rather than setting it aside.
Sperm DNA Fragmentation Test
A sperm DNA fragmentation test measures the share of sperm carrying damaged DNA. Labs report it as a DNA fragmentation index, or DFI. A few methods are in common use:
- SCSA (sperm chromatin structure assay)
- TUNEL assay
- SCD, or Halosperm
- Comet assay
Many labs treat a DFI under 15% as low and above 30% as high, though the cut-offs shift from one lab and test to another. A specialist usually suggests the test after unexplained infertility, repeated IVF failure, or recurrent miscarriage, rather than as a routine check for every couple.
What Can Lower Sperm DNA Fragmentation
Several steps can bring the damage down. Treating a varicocele, where enlarged veins in the scrotum raise temperature and oxidative stress, has solid evidence behind it in the right patients. Everyday changes help too: stopping smoking, managing weight, avoiding excess heat, and clearing any infection. Some doctors suggest antioxidant supplements, though the evidence for them stays mixed. For IVF itself, advanced sperm selection, or in some cases using sperm taken directly from the testicle, can reduce the DNA damage that reaches the egg.
When IVF fails more than once, the male side deserves a proper look, not just a basic semen report. The fertility and andrology team at 9M Fertility can assess male factor infertility, explain whether a sperm DNA fragmentation test suits the situation, and talk through the options if the result comes back raised. If you have been through more than one failed cycle, that is a sensible next conversation to have: https://www.9mfertility.com/contact-us/
