Even in the best fertility clinics, transferring a healthy embryo into the uterus leads to a live birth only about half the time. In 30% to 35% of cases, the embryo does not implant at all. Other times, implantation happens but the pregnancy ends in miscarriage.

For years, most fertility research has focused on the embryo. But new research from Michigan State University and Rutgers Health suggests that the health of the uterus itself may be a key part of the puzzle.

The study, recently published in JCI Insight, identifies genes in the uterine lining, or endometrium, that activate in fertile women when the uterus enters its brief window of receptivity. The research was supported by three grants from the National Institutes of Health, including the Eunice Kennedy Shriver National Institute of Child Health and Human Development.