Researchers found faulty levels of a protein that regulates fluid balance in parts of the womb can prevent implantation or trigger a miscarriage.
The discovery suggests drugs could target the faulty protein to prevent the conditions.
Researchers from Imperial College London found that, among women who had unexplained infertility, levels of the kinase protein SGK1 were higher in a section of the womb lining.
Yet among women who had lost three or more pregnancies in a row, levels of the protein were far lower in a different set of tissues of the endometrium.
Researchers bred mice to carry mutations that affected the protein’s production in these tissues.
Much higher levels of the protein disrupted the manufacture of proteins involved in the implantation of the fertilised egg. They also affected the womb environment. Together, these effects caused infertility.
Mice bred to have reduced SGK1 activity during pregnancy failed to protect against oxidative stress during the extensive tissue changes, which led to loss of the foetus.
Researchers concluded: ‘Deregulation of a single kinase in two distinct cellular compartments of the endometrium – the luminal epithelium and underlying stroma – is intricately linked to subsequent implantation failure and miscarriage, respectively.’
Around one in eight pregnancies that are known to the mother end in miscarriage. Recurrent miscarriage affects around one in 100 women.