STUDIES ON RELATION BETWEEN SERUM OXYTOCINASE AND COURSE OF LABOR

Assay of serum oxytocinase levels by the chemical method, using L-cystine-di-β-naphthylamide as substrate and the dynamic oxytocin test with Syntocinon were made in 136 hospitalized pregnant women before delivery. A statistically significant relationship was found between prenatal levels of serum oxytocinase and the following clinical data: body surface of the fetus, state of neonate, placental weight, perinatal blood loss, and duration of labor. No differences were found in the level of the enzyme when the reactivity of the pregnant uterus to oxytocin was in the range of 10 to 60 mU. of Syntocinon injected intravenously. However, the serum oxytocinase level in women requiring administration of oxytocin for induction of labor was significantly lower than in other parturient women, regardless of whether delivery was spontaneous or operative. The observed facts were explained in the light of a biochemical theory concerning pregnancy and labor. © 1969.