Colloid osmotic pressure at birth. Effect of sample site, type, and mode of delivery.

Colloid osmotic pressure was measured at birth in 102 newborns. Umbilical vein plasma colloid osmotic pressure correlated with total serum protein, birth weight, and gestational age. Mean colloid osmotic pressure of 11 infants who were small for gestational age was less than, and that of seven infants who were large for gestational age was more than, that of average-sized infants of similar gestation. For infants weighing 1,501 to 3,000 g, mean (+/- SD) colloid osmotic pressure following cesarean section (15.1 +/- 1.6 mm Hg) was lower than that following vaginal delivery (18.4 +/- 2.2 mm Hg). This may reflect the fact that use of maternal fluid therapy preceding cesarean section was greater than before vaginal delivery. The definition of normative values for neonatal plasma colloid osmotic pressure makes it possible to investigate changes in relation to disease, therapy, and subsequent outcome in sick neonates.