What is decidua?

The decidua is an obstetric term that refers to the uterine lining, i.e. the endometrium during pregnancy. When pregnancy occurs, the endometrial tissue thickens and becomes vascularized, favoring embryo implantation and, therefore, an evolving pregnancy.

This layer participates in the exchange of gases, nutrients and waste products between the mother and the fetus, but also serves as a protective barrier.