Womb lining linked to repeated miscarriages

Problems with the womb lining before pregnancy may help explain why some women experience multiple miscarriages despite having healthy embryos, UK researchers have found.

The study, which analysed over 1,500 biopsies from more than 1,300 women, identified a recurring issue with a biological process called the decidual reaction.

This monthly transformation of the womb lining prepares it for potential pregnancy.

When the process is faulty or becomes dysregulated, it creates a less stable environment for implantation, increasing the risk of early pregnancy loss.

Researchers found that the abnormal response in the womb lining recurred across menstrual cycles far more frequently than would be expected by chance.

 Dr Joanne Muter, lead author from Warwick Medical School, said: “This is about identifying preventable miscarriages.

Many women are told they’ve just had ‘bad luck’, but our findings show that the womb itself may be setting the stage for pregnancy loss, even before conception takes place.

The findings also revealed that experiencing one miscarriage increases the likelihood of abnormal womb lining responses in subsequent cycles.

Around one in six pregnancies end in miscarriage, mostly before 12 weeks.

Professor Jan Brosens is professor of obstetrics and gynaecology at Warwick and UHCW NHS Trust and scientific director at Tommy’s National Centre for Miscarriage Research.

Brosens said: “It is well-established that chromosomal errors in embryos account for the rise in miscarriage rates in women older than 35 years.

“This study shows that each miscarriage increases the risk of an embryo implantation in an abnormal womb lining, regardless of age.

“Thus, the frequency of one of two events – abnormal embryo or abnormal decidual reaction – happening over hundreds of menstrual cycles determines the likelihood of miscarriage in each individual woman.

Importantly, we now have the tools to screen for the risk of preventable miscarriage and to evaluate treatments that improve the womb lining before pregnancy.

A diagnostic test has been developed to assess molecular signals in the womb lining, indicating whether the decidual reaction is functioning normally.

The test is being piloted at University Hospital Coventry and has already supported over 1,000 patients.