Stalling of the endometrial decidual reaction determines the recurrence risk of miscarriage

Muter et al. — Science Advances, 2025

Miscarriage affects roughly one in three pregnancies following implantation, and for women who experience it more than once, the reasons are rarely clear. Maternal age and embryo aneuploidy account for some of the risk — but they don't explain everything, particularly in younger women or those with chromosomally normal losses.

This study, published in Science Advances, offers a new framework. Analyzing endometrial biopsies from 924 women, the research team found that a weakened or stalled decidual reaction — not embryo quality alone — closely tracks with recurrence risk. The decidual reaction is the process by which stromal cells in the womb lining transform to create an implantation niche and, ultimately, the decidua that anchors and sustains a pregnancy.

What the research found

The study identified two key cell populations driving the reaction: progesterone-resistant DIO2+ stromal cells that form the implantation niche, and progesterone-dependent PLA2G2A+ predecidual cells that expand in their place. When this sequential transition stalls, the endometrial environment becomes permissive to implantation but inadequately prepared for decidual transformation — a setup for loss.

Critically, prior miscarriages were found to disrupt intercycle endometrial homeostasis, meaning each loss can erode the decidual reaction further. The recurrence risk, the authors conclude, reflects the endometrium's diminishing capacity to sustain a pregnancy — irrespective of maternal age.