A new study has revealed that in some cases, recurrent pregnancy loss may be caused by sperm DNA damage in the male partner.

The study presented at ENDO 2019, the Endocrine Society's annual meeting in New Orleans, La., says that the repeat miscarriage may be caused by sperm DNA damage rather than by a problem in affected women. "Our study suggests that it may be useful to investigate if male partners of women with RPL have abnormalities in their reproductive function," said lead researcher Channa Jayasena, MD, Ph D, of Imperial College of London, UK.

"It also opens up a new potential 'drug target'. It may be possible to design future drugs to stop sperm DNA damage to treat couples with RPL and reduce the risk of miscarriage," added Jayasena. Between one and two per cent of couples have recurrent pregnancy loss (RPL), defined as the consecutive loss of three or more pregnancies before 20 weeks gestation.

"Affected women undergo many tests to determine the cause, but many cases have no identified cause," said Jayasena. Male partners of women with RPL do not routinely undergo an assessment to see if they play a role. "However, we know that sperm plays an important role in the formation of the placenta, which is critical for the survival of an unborn baby," said Jayasena.

The study was designed to assess whether male partners of women with RPL may have an increased risk of sperm DNA damage, which is known to impair fertility. The researchers compared 50 healthy men whose partners had not experienced miscarriages with 63 men whose partners were affected by RPL. They measured levels of sex hormones such as testosterone, the number, and behaviour of sperm using a microscope, and further molecular tests.

Also, they measured the level of damage to sperm DNA, and level of a chemical entity called reactive oxygen species, which can damage cells such as sperm in the semen of men. They found out that the men affected by RPL had twice sperm DNA damage compared with the unaffected men. Men whose partners had suffered miscarriage also had a four-fold increase in the number of reactive oxygen species compared with unaffected men.