Serum Alkaline Phosphatase in Pregnancy

Abstract

Total and heat-stable alkaline phosphatase levels in serum were determined in pregnant women at various gestational periods. A correlation between levels of the heat-stable enzyme on the one hand and urinary estrogens and birth weights of infants on the other was sought. It was observed that both the total and heat-stable fraction of the enzyme increased with advancing gestation. The levels of heat-stable fraction were found to be higher at term in women belonging to low income groups compared with women belonging to high income groups. However, no correlation was observed between the urinary estriol excretion and the levels of heat-stable enzyme. An inverse correlation was seen between birth weights of infants and the heat-stable alkaline phosphatase activity at term. Though the heat-stable alkaline phosphatase in serum is of placental origin its level in serum does not appear to be a reliable index of placental function.