Recurrent miscarriage is defined as having three or more miscarriages in succession and is a heartbreaking event that affects one in 100 women trying to conceive. Scientists are now claiming to have identified a cause, finding a lack of stem cells in the womb lining to be the culprit behind continued failed pregnancies, and aims to begin developing treatments to bolster populations of these cells later in the year.

Working with tissue samples from the womb lining provided by 183 donors, researchers at the UK's University of Warwick found lower levels of stem cells in the womb lining from women who had suffered recurrent miscarriages when compared to the control group.

Because the ability of the womb's lining to renew itself relies on the resident stem cell population, the team found that this deficiency sped up the aging of the womb. The aging cells in turn mount an inflammatory response, which hinders the development of an implanted embryo.

"After an embryo has implanted, the lining of the uterus develops into a specialized structure called the decidua, and this process can be replicated when cells from the uterus are cultured in the lab," says Professor Jan Brosens, leader of the research team. "Cultured cells from women who had had three or more consecutive miscarriages showed that aging cells in the lining of the womb don't have the ability to prepare adequately for pregnancy."

Through this new understanding of the role of stem cells in pregnancy, the researchers are now hopeful of developing treatments that can boost their populations in the womb.

"We will start piloting new interventions to improve the lining of the womb in the spring of 2016," says Siobhan Quenby, co-author of the study. "Our focus will be two-fold. First, we wish to improve the screening of women at risk of recurrent miscarriage by developing new endometrial tests. Second, there are a number of drugs and other interventions, such as endometrial 'scratch', a procedure used to help embryos implant more successfully, that have the potential to increase the stem cell populations in the womb lining."

The research was published in the journal Stem Cells.