What is DNA Fragmentation?
Studies indicate DNA fragmentation impacts fertility and healthy pregnancies. Let’s dive into what it is.
One would think that a high sperm count, combined with good motility (swimming ability) and morphology (sperm shape), would prove indicative to a healthy degree of fertility in men. Unfortunately, these factors alone do not correlate to high fertility, especially when you consider the implications of DNA fragmentation.
While the term looks as though it belongs as part of the regular maintenance of a person’s computer drive, the impact DNA fragmentation has on a couples’ chances of conceiving is far more serious than initially thought. In fact, a high amount of fragmented DNA can result in reduced male fertility, subpar embryo development, and less successful rates of implantation.
What is DNA fragmentation?
In an age when a small amount of high-quality sperm can lead to pregnancy through in vitro fertilization, the integrity of genetic material in sperm is essential for successful fertilization and normal embryo development. Sperm DNA fragmentation is a term used to identify abnormal genetic material within the sperm, which may lead to male subfertility, IVF failure, and miscarriage.
Healthy DNA is distinguished by a double-helix spiral held together by cross-bonds that together appear to form the shape of a ladder. However, when any of the DNA “rungs” become broken or unstable, the whole genetic ladder becomes unsteady. This results in sperm fragmentation. DNA fragmentation can lead to chromosomal abnormalities, which can contribute to birth defects. While all of the various causes of sperm fragmentation are not yet known, common causes include age, smoking, infection, testicular cancer, heat exposure, and toxin/chemical exposure.
A recent New York Times article, featuring renowned fertility expert Dr. Paul Turek, explains that our DNA tends to progressively break down as we age. Subsequently, the older a man gets, the greater the chances of DNA fragmentation. As men experience DNA fragmentation, this leads to a higher chance of infertility or miscarriages.
Read more about male fertility and age.
DNA fragmentation and recurrent pregnancy loss
Not only does DNA fragmentation directly correlate to lower fertility in men, but it is also linked to recurrent pregnancy loss (two or more failed pregnancies). A 2018 study published in the Middle East Fertility Society Journal examined the role that fragmented DNA plays in recurrent pregnancy loss (RPL).
Through the course of the study, researchers conducted a 2-year retrospective review of 149 couples. Sixty-seven of the study participants had partners who were healthy and had “normal karyotype,” which refers to the number and appearance of the chromosomes present in a cell. The study found that “cytogenetic abnormality [chromosomal defect] is one of the most common causes of recurrent fetal loss.”
The study also confirmed that 75 percent of the sperm samples from couples experiencing RPL demonstrated an ideal sperm count, motility, and morphology. Subsequently, the authors of the study stated that this fact “…drives home the limitation of routine semen examination in detecting sperm defect abnormalities.” At the conclusion of the study, researchers determined that testing for “sperm DNA integrity” could prove “valuable” for couples struggling to conceive.
The validity of sample testing
Exactly how valuable testing for sperm DNA integrity remains unclear. In a 2017 study entitled Finding the fit: Sperm DNA integrity testing for male infertility, the aforementioned Dr. Turek examined the semen analysis test that is often used to evaluate male fertility. He concluded, “…the concept that fertility is defined by threshold values of semen parameters is fundamentally flawed”. In particular, he noted tests to determine sperm DNA fragmentation led to results that were “nothing to brag about.” He suggested that both time and further research were needed to undeniably support sperm integrity testing.
While conclusive answers about the ability to test for DNA fragmentation have yet to be presented by the scientific community, it remains well accepted that sperm fragmentation leads to complications, including miscarriage and infertility. Rather than wait for a definitive test, it stands to reason that men should take steps that can reduce the effects of DNA fragmentation.
In addition to tests, men should also curtail or eliminate negative behavioral habits, such as smoking, drinking, and needless exposure to toxins and pollutants. According to a leading fertility clinic in the U.K., men should also strive to eat a balanced diet, as naturally occurring antioxidants appear to help in battling DNA fragmentation.
Daily sex linked to reduced sperm fragmentation
Research suggests that the amount of sex a man has can impact their sperm quality. A 2009 study published by the European Society of Human Reproduction and Embryology (ESHRE) suggests that men who have daily sex can reduce sperm DNA fragmentation.
On the other hand, a 2013 study suggests that having sex each and every day might not be as effective in reducing sperm DNA fragmentation as creating a schedule that includes a day of abstinence. Researchers writing in the Journal for Assisted Reproduction and Genetics concluded that just one day of abstinence resulted in a reduction of sperm fragmentation in 90% of the subjects tested.
This article was contributed by our friends at Legacy. Legacy is the fatherhood company, helping men test or freeze their sperm without having to visit a doctor's office. Incubated at Harvard University, Legacy is run by a team of healthcare and fertility experts who believe in changing the outdated view that fertility is a 'women's issue.' Legacy is available nationwide for men or couples thinking about family planning or fertility preservation.