Infant size and relative placental weight at birth

In 811 unselected term infants, the ratios of placental weight to (a) body weight, (b) head circumference and (c) body length were assessed as possible determinants of infant size at birth. Unlike the placentofetal weight ratio, the ratio of placental weight to either head circumference of body length proved an excellent predictor of infant size, ponderal index and skinfold thickness. Infants with a relatively small placenta at term were growth-retarded when compared to infants with relatively large placentas. It is suggested that the ratio of placental weight to either head circumference or body length at term reflects not only relative placental size but also the functional capacity of the placenta to meet the nutritional demands of the fetus.