Pathology of the placenta: A Continuum Spectrum of Inflammation from Physiology to Disease

Successful pregnancy is the result of a delicate balance between fetal demands and maternal supply. The feto-maternal interface is the no man’s land for this dialogue. Immune cells set the rules of the feto-maternal cross talk, pipeline development, cell functions, and reactions to unexpected third parties. A dynamic and coordinate modification of number, morphology, function, and distribution of any type of inflammatory cells sustains the normal evolution of pregnancy and eventually helps to bring it to parturition. Abnormalities in the equilibrium of the inflammatory microenvironment can lead to placental histological lesions and adverse pregnancy outcome. Beyond acute infections, chronic villitis, chronic chorioamnionitis, chronic intervillositis, and chronic deciduitis often coexist as a tetrad, suggesting an abnormal immune response. Maternal characteristics such as visceral obesity could set the ground for the development of these placental lesions.