Recurrent Miscarriage Linked To Faulty Sperm
The early-stage study, from scientists at Imperial College London,
investigated the sperm quality of 50 men whose partners had suffered
three or more consecutive miscarriages.
The research, published in the journal Clinical Chemistry,
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 hope these findings may open new avenues to finding treatments to reduce the risk of miscarriage.
Recurrent miscarriage affects around one in 50 couples in the UK, and is
defined as the consecutive loss of three of more pregnancies before 20
weeks gestation.
Until recently recurrent miscarriage was thought to be caused by health
issues with the mother, such as infection or immune problems.
However, doctors are now realising sperm health may also play a role,
explained Dr Channa Jayasena, lead author of the research from
Imperial’s Department of Medicine: “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 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.”
In the new research, the team analysed the sperm of 50 men who were
patients at the Recurrent Miscarriage Clinic at St Mary’s Hospital in
London, part of Imperial College Healthcare NHS Trust.
They then compared the results to the sperm health of 60 male volunteers whose partners had not suffered miscarriage.
The analysis revealed sperm from men with partners who had suffered
recurrent miscarriage had twice as much DNA damage compared to the
control group.
The research team suggest this 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 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.
The research team are now investigating what may trigger high levels of these reactive oxygen species.
Dr Jayasena explained: “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 there is increasing evidence obesity can lower sperm health –
possibly because high levels of body fat can trigger an increase in
reactive oxygen species. Therefore the team are analysing the metabolic
health of the 50 men in the study, and assessing weight and cholesterol
levels.
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 are now investigating whether
these factors may have affected the levels of reactive oxygen species.
Dr Jayasena concluded: “Although this is a small study, it gives us
clues to follow. If we confirm in further work that high levels of
reactive oxygen species in semen increase the risk of miscarriage, we
could try to develop treatments that lower these levels and increase the
chance of a healthy pregnancy.
“It has taken medicine a long time to realise sperm health has a role to
play in miscarriage – and that the cause doesn’t lie solely with women.
Now we realise 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.”
The work was supported by the Medical Research Council, Biotechnology
and Biological Sciences Research Council, and the National Institute for
Health Research Imperial Biomedical Research Centre.