It is a surprising fact that there are relatively few quantitative estimations1of the gonadotropic hormone in the urine of normal pregnancy, attention having been directed mainly to the remarkable diagnostic reliability of the Aschheim-Zondek test. It is, however, well established that abnormally high levels of the hormone are found in the blood, urine and cerebrospinal fluid in hydatidiform mole and chorionepithelioma. Emphasis has therefore been placed on the need for quantitative hormone estimations in all cases suggesting either of these two types of pathologic alteration of pregnancy.2In the present communication we propose to report what we believe to be the invariable occurrence of the earlypeak phenomenon as regards the gonadotropic content of blood and urine in all normal human pregnancies—a transient and remarkable rise in gonadotropic hormone followed by a fall to values of a few thousand units perliter. This transient hormone concentration at its