Recurrent miscarriage, defined as the consecutive loss of three of more pregnancies before 20 weeks gestation, has been linked to faulty sperm.
Scientists at Imperial College London, who investigated the sperm quality of 50 men whose partners had suffered three or more consecutive miscarriages compared the results to the sperm health of 60 male volunteers whose partners had not suffered miscarriage.
The result revealed that, compared to men whose partners had not experienced miscarriages, the sperm of those involved in the study had higher levels of DNA damage.
The study team hopes these findings may open new avenues to finding treatments to reduce the risk of miscarriage.
Until recently, recurrent miscarriage was thought to be caused by health issues with the mother, such as infection or immune problems but the lead author of the study from Imperial’s Department of Medicine, Dr Channa Jayasena said, doctors are now realising sperm health may also play a role.
He explained that traditionally, doctors have focused attention on women when looking for the causes of recurrent miscarriage, adding that men’s health and the health of their sperm, wasn’t analysed.
“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 foetus,” he explained.
The research team suggests that DNA damage may be triggered by so-called reactive oxygen species.
“There are molecules formed by cells in semen (the fluid that contains sperm cells) to protect sperm from bacteria and infection. However, in high enough concentrations the molecules can cause significant damage to sperm cells.”
The results from the study revealed that sperm from men whose partners had suffered miscarriage had a four-fold increase in the amount of reactive oxygen species compared to the control group.
Dr Jayasena explained further, that “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.”
He added that there is increasing evidence that obesity can lower sperm health, possibly because high levels of body fat can trigger an increase in reactive oxygen species. “Therefore the team is analysing the metabolic health of the 50 men in the study, and assessing weight and cholesterol levels,” he said.
The men whose partners had suffered miscarriage were also slightly older than the control group with an average age of 37 compared to 30, and were slightly more overweight. The team is now investigating whether these factors may have affected the levels of reactive oxygen species.