Multiple miscarriages may be linked to faulty sperm, study finds

LONDON — There may be no worse tragedy for an expecting couple than a miscarriage, and the idea of recurring miscarriages is almost too awful to even imagine for many soon-to-be parents. Miscarriages often leave parents searching for answers, but now a new study may be able to provide some insight.

Researchers at Imperial College London say they have found a link between recurring miscarriages and the quality or lack thereof, of a man’s sperm. To put it succinctly, low-quality sperm may cause multiple miscarriages.

The early-stage study analyzed the sperm quality of 50 men whose partners had suffered three or more consecutive miscarriages. The results showed that, when compared to men whose partners had not experienced miscarriages, the sperm of those in the study had higher levels of DNA damage.

Researchers are hopeful that their findings will help establish new treatments to reduce the rate of miscarriages. For example, recurrent miscarriages happen to about one in 50 heterosexual couples in the United Kingdom. If this research can help prevent even a few miscarriages in the future it would make the research team’s efforts an undisputed success.

For the most part, recurrent miscarriages are usually thought to be caused by health issues experienced by the mother, such as infections and immune system problems.

“Traditionally doctors have focused attention on women when looking for the causes of recurrent miscarriage. The men’s health – and the health of their sperm – wasn’t analyzed,” says study lead author Dr. Channa Jayasena, of Imperial’s Department of Medicine, in a media release. “However, this research adds to a growing body of evidence that suggests sperm health dictates the health of a pregnancy. For instance, previous research suggests sperm has an important role in the formation of the placenta, which is crucial for oxygen and nutrient supply to the fetus.”

The research team compared the sperm of 50 men who were patients in the Recurrent Miscarriage Clinic at St. Mary’s Hospital of London with 60 male volunteers whose partners had not suffered miscarriages. The analysis showed that men with partners who suffered from recurrent miscarriages had twice as much DNA damage in their sperm compared to the control group.

Researchers hypothesized that the observed DNA damage may have been triggered by what they called reactive oxygen species. These molecules are created by semen cells in order to protect sperm from bacteria and infections, but high concentrations can have an adverse effect on sperm cell DNA.

The study’s analysis revealed that the sperm samples from men whose partners had suffered multiple miscarriages displayed a four-fold increase in the amount of reactive oxygen species compared to the other group of men. Moving forward, the research team are investigating what may cause this spike in reactive oxygen species.

“Although none of the men in the trial had any ongoing infection such as chlamydia – which we know can affect sperm health – it is possible there may be other bacteria from previous infections lingering in the prostate gland, which makes semen. This may lead to permanently high levels of reactive oxygen species,” Dr. Jayasena comments.

Researchers also noted that obesity is believed to damage sperm quality and possibly cause an increase in reactive oxygen species, so they are in the process of investigating the metabolic health, weight, and cholesterol levels of all 50 men involved in the experimental group. Furthermore, men whose partners had suffered multiple miscarriages were a bit older than the men in the control group, leading researchers to speculate if age plays a role in reactive oxygen species development as well.

“It has taken medicine a long time to realize sperm health has a role to play in miscarriage – and that the cause doesn’t lie solely with women. Now we realize both partners contribute to recurrent miscarriage, we can hopefully get a clearer picture of the problem and start to look for ways of ensuring more pregnancies result in a healthy baby,” Dr. Jayasena concludes.

The study is published in the journal Clinical Chemistry.

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