Developmental aspect of decidual patterning

In clinical practice, early pregnancy loss has afflicted approximately 15%–25% women of reproductive age worldwide, which is partially attributed to defects associated with the endometrium. During pregnancy, the endometrial stromal cells experience remarkable tissue remodeling and transformation, termed as decidualization, to support embryonic development, placental formation, and the maintenance of normal pregnancy in both mice and human. During this process, a series of dynamic developmental events, including rapid stromal proliferation, increased stromal cell size, enhanced angiogenesis, taken place in a highly-ordered manner under the precise regulation of steroid hormones. Meanwhile, diverse molecules exhibit spatiotemporal-specific expression pattern, implying their unique roles in decidual development. To achieve a more comprehensive understanding of these biological events and explore the underlying causes of early pregnancy disorders, this review emphasizes on the detailed developmental progression of decidual transformation and patterning as well as related pregnancy complications at the early stage of pregnancy.