The human newborn infant has hypoprothrombinemia in a moderate degree at birth,1 in greater degree between the second and the sixth day of life2 and in gradually diminishing degree throughout the first twelve months of life.1 The causes for this deficiency remain obscure. This hypoprothrombinemia, which renders the newborn infant susceptible to profuse loss of blood, has been attributed to a possible dietetic deficiency in the mother, though plasma prothrombin values in the mother at term are usually higher than normal.3 The condition develops too early in the newborn infant to be attributable to a food deficiency in the child. The lack of a well developed bacterial flora in the intestine has been suggested as another cause.2a
A rare anomaly observed in a full term mulatto infant cast light unexpectedly on the mechanism of this deficiency.
On the second day of life the infant became intensely jaundiced and
TOCANTINS LM. PROBABLE MECHANISM OF THE "PHYSIOLOGIC" HYPOPROTHROMBINEMIA OF THE NEWBORN. Am J Dis Child. 1940;59(5):1054-1056. doi:10.1001/archpedi.1940.01990160126007