Chronic Histiocytic Intervillositis (CHI or CHIV) also known as Chronic Intervillositis of Unknown (A)etiology (CIUE) and Massive Chronic Intervillositis (MCI) is defined as a diffuse infiltration of mononuclear cells (histiocytes, lymphocytes, monocytes) of maternal origin into the intervillous space within the placenta. It often results in severe intrauterine growth restriction which can lead to miscarriage or stillbirth. Overall perinatal mortality rate is high: 41%. to 77%. Recurrence rate is also high: 67% to 100% Chronic Histiocytic Intervillositis (CHI or CHIV) also known as Chronic Intervillositis of Unknown (A)etiology (CIUE) and Massive Chronic Intervillositis (MCI) is defined as a diffuse infiltration of mononuclear cells (histiocytes, lymphocytes, monocytes) of maternal origin into the intervillous space within the placenta. It often results in severe intrauterine growth restriction which can lead to miscarriage or stillbirth. Overall perinatal mortality rate is high: 41%. to 77%. Recurrence rate is also high: 67% to 100%