Placental villous edema: a possible cause of antenatal hypoxia.

This study was undertaken to determine the relationship between the placental villous edema and the characteristic sequelae of antenatal hypoxia, i.e. the need for resuscitation at birth and low pH values in umbilical arterial blood. Placental villous edema was recognized by finding of open spaces within the cytoplasm of intervillous cells and in the interstitium of the villi. The percentage of edematous villi was significantly higher in the group of newborns requiring resuscitation. The severity of the edema had a positive correlation with the need for resuscitation at birth and with the arterial blood pH values in the umbilical cord. Placenta praevia and maternal toxicosis were associated with high percentage of edematous villi. It is suggested that edema fluid interposed a barrier to gas exchange between mother and fetus. The capillaries were blocked by compression leading to reduction in blood flow through the villi. These abnormalities, if widespread, may reduce gas exchange. It is suggested that hypoxia could partly be prevented by preventing the development of placental villous edema.