This work recapitulates 30 years of clinical experience in the enzymatic monitoring of pregnancy and prediction of birth date. It discusses the scale for indicating biological gestational age, and predicting birth date, making full use of the clinical possibilities provided by pregnancy monitoring based on oxytocinase-determination and ultrasonography. The contents include chapters on biological and calendar gestatational age, the biochemical monitoring of pregnancy, biochemical methods of oxytocinase-determination, oxytocinase monitoring of high-risk pregnancies, and the enzymatic and ultrasonographic prediction of birth date.