One of the most dangerous risks expectant mothers face as their delivery date approaches is a surprisingly common condition with a little-known name: placental accreta.

In normal childbirth, the placenta is delivered shortly after the newborn infant. But sometimes, the placenta becomes so deeply attached to the woman’s uterus that it cannot be removed without causing massive, sometimes fatal bleeding. In many cases, the emergency surgery needed to save the mother’s life can leave her unable to have any more children.

And yet, many people do not know about placental accreta, even though the number of women diagnosed with it has quadrupled since the 1980s to one in every 272 births.

The day to detect and proactively treat accreta may have moved a step closer, thanks to a discovery made by scientists at Cincinnati Children’s and the University of Cincinnati.

In a study published in Science Immunology, co-authors describe a surprising connection between accreta risk and a gene mutation that prevents healthy formation of “natural killer” cells—a type of white blood cell that helps the body fight off cancer tumors and viral infections. Beyond discovering the connection, the team further demonstrated, in mice, that accreta can be stopped in its tracks.

“This is a huge issue for maternal health,” said study co-author Helen Jones, PhD, Center for Fetal and Placental Research. “Currently, the only way to diagnose accreta is to spot it mid-pregnancy on ultrasound, usually after 18 to 20 weeks. Many women never know they have it until they arrive at the hospital for labor and delivery.” 

Previous studies have shown that accreta risk rises sharply when women have multiple C-sections. These findings may help explain why, added Jones.

If future studies confirm that women facing accreta also have malfunctioning NK cells, it may become possible to prevent over-attachment and reduce the need for fertility-ending hysterectomies.

Observations from the basic-science project of Kasper Hoebe, PhD, a scientist formerly with the Division of Immunology, and Anna Sliz, graduate student, contributed to the new finding. 

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