Sperm DNA damage could be a factor in recurrent miscarriages: study
A new study is giving a glimmer of hope to couples affected by repeated miscarriages after investigating a new possible cause to the rare and relatively obscure condition – sperm anomalies.
For couples looking to expand their family, a miscarriage could be a traumatizing experience. And for an estimated one percent of those trying to have a baby, the horror repeats itself over and over again due to a condition known as Recurrent Pregnancy Loss, or RPL.
RPL is historically defined as the consecutive loss of at least three pregnancies before the 20th week of gestation, although the European Society of Human Reproduction and Embryology brought the number of pregnancy failures down to two in updated guidelines last year.
In their quest to identify the underlying factors, researchers have traditionally focused on women affected by RPL and isolated a number of medical issues that could potentially contribute to a spontaneous termination of pregnancy. Chromosomal defects, uterine malformation, incompetent cervix, diabetes, and autoimmune disorders have all been found to be possible culprits.
However, more often than not, the cause remains a mystery. In fact, over half of the cases are idiopathic, according to the UK charity The Miscarriage Association, while The American College of Obstetricians and Gynecologists estimates that between 50 and 75 percent of the cases go unexplained.
So researchers at the Imperial College London turned their focus on paternal factors.
"We know that sperm play an important role in the formation of the placenta, which is critical for survival of an unborn baby," said Channa Jayasena, the lead researcher of the study presented at the Endocrine Society's annual meeting in New Orleans over the weekend.
Jayasena and his team were interested in the sperm characteristics of male partners of women who have experienced recurrent miscarriages, specifically endocrine and metabolic sperm functions. They recruited 50 men whose partnered had never suffered pregnancy losses and 63 men whose partners were affected by RPL for semen analysis.
They assessed the levels of reproductive hormones, including testosterone, and the sperm count, motility and morphology, among other characteristics. The researchers also ran molecular tests to evaluate the levels of oxidative stress in the semen and sperm DNA damage.
Oxidative stress is caused by a compound called reactive oxygen species (ROS). They're normally produced by the body but when in excessive numbers, they damage the sperm and the DNA embedded in the sperm, affecting male fertility.
Researchers found that levels of semen ROS where four-fold higher in men affected by RPL than in their counterparts whose partners never underwent miscarriages, while levels of DNA fragmentation in the former were twice as much as those in the latter.
"Male partners of women with RPL have reduced concentrations of serum testosterone and estrogen when compared with controls, which warrant further investigation. We also report markedly increased levels of semen ROS and sperm DNA fragmentation and reduced functional sperm parameters when compared with control participants," the study read.
A miscarriage increases the risk of unsuccessful pregnancies in the future by 14 to 21 percent following the first loss, 24 to 29 percent following the second miss, and 31 to 33 percent in the wake of a third failed time. And although six out of 10 women with RPL go on to have a full-term pregnancy later on, according to estimates, the elusive reasons behind recurrent pregnancy losses hinder targeted therapies for couples looking to conceive.
The study is the latest in a recent body of work looking at underlying causes of RPL outside of the woman's body and probing the possible male implication in the condition. Findings are suggesting a new approach in dealing with couples who have experienced recurrent miscarriages by examining the male partners for possible reproductive problems, and pave the way for more precise treatment plans.
(CGTN)
