To determine the components of the pathogenesis of antenatal fetal hypoxia with stillbirths (n=55) and fetoplacental insufficiency (FPI) with live births (n=46), comparisons were made on morphological changes in 55 and 46 placentas, respectively, and the clinical parameters of the fetoplacental unit (FPU) in 46 pregnant women with varying degrees of FPI who had delivered a live fetus. The clinical and morphological features of FPU with the critical status of a fetus and progressive FPI bear significant similarities to those in the group of antenatal deaths: these are characterized by premature villous maturity, basal lamina pathology, multiple infarctions, dramatic neonatal weight loss and develop in the same periods (at weeks 32-35.5); early-onset severe gestosis plays a leading role in the pathogenesis of FPU changes. The clinical and morphological features of FPU with compensated FPI characterized by the best perinatal outcomes excel in the villous tree that is mature in regard to full-term gestation with the lowest placental mass, few focal changes, and low neonatal weight-for-height values. The causes of placental immaturity with reference to the gestational period in some antenatal deaths are yet to be explained. Comparative clinical and anatomical studies show that the correspondence of placental villous maturity with the gestation period plays a crucial role in the pathogenesis of FPI and antenatal deaths and the structure of villi is determined by the status of a pregnant woman.