Sperm deoxyribonucleic acid (DNA) fragmentation is damage to the DNA, or the critical hereditary material, of sperm. Since a sperm delivers one half of the chromosomes that will eventually become a human being if it fertilizes an egg, this can have a dramatic effect on a couple's ability to conceive. Unfortunately, sperm DNA fragmentation can result in infertility, or the reduced ability to achieve a pregnancy, and miscarriage. Damaged sperm DNA can occur in men of all ages, but the risk generally increases as a man ages — the rate of sperm DNA fragmentation is often dramatically higher in a man who is 55 than a man who is 20 years old.
Often, problems with a couple's ability to conceive a child and carry it to term are associated with female issues. For example, if a woman has a miscarriage, stillbirth, or fails to get pregnant at all, doctors often suspect that there is something wrong with her eggs, hormone levels, uterus, cervix, ovaries, or Fallopian tubes. Sometimes, however, the male partner has fertility issues, such as blocked ducts in his penis, low sperm count, or reduced sperm motility, that are present. In some cases, however, a man can have a normal amount of sperm and no motility issues but have a high percentage of sperm DNA fragmentation.
Sperm DNA fragmentation basically just means that the sperm's DNA is damaged. The DNA in sperm is packed into a very small space, and protein is wrapped around the DNA in order to provide protection as the sperm travels out of the male body and through the female's reproductive system. Unfortunately, this doesn't provide total protection for the DNA, and even with this protein present, it is still possible for the DNA to become damaged.
It is important to note that even men with good sperm counts and otherwise healthy sperm can have some amount of sperm DNA fragmentation. Fragmentation is not dependent on the sperm count at all. In fact, most men have the problem to some extent. It is when the percentage of damaged sperm gets too high, however, that fertility problems are more likely to occur.
There are many things that have the potential to cause an increase in sperm DNA fragmentation. Among them are increasing age, exposure to toxins, infections, and smoking. Cancer and radiation exposure can cause this issue as well.