Synopsis of change Pre-1900s Understanding of circulation, and the transition at birth from placental to pulmonary respiration. Early 20th century Introduction of a clamp as alternative to tying the umbilical cord.  Instructions for use always began with the need to wait for pulsations of the cord to cease before applying the clamp. Research continued on measuring the amount of blood transferred from placenta to lungs of the newborn. 1930s More varieties of clamps were introduced. Clamping before pulsations of the cord ceased came into practice. Banking of placental blood for transfusions was begun. 1940s Anemia in infancy was linked to early clamping of the cord. Autism was described by Kanner (1943) in children born during the 1930s. Rh antigen discovered as cause of blood hemolysis and jaundice in newborn infants. 1950s Aogar introduced her scoring system, a measure of "respiratory depression." Clamping of the cord immediately after birth was practiced more and more, as a means to preserve a "sterile field," especially for cesarean births. Respiratory distress was reported more frequently, especially in infants born by cesarean section, and in thoroughbred foals born with human assistance. 1960s Pro and con camps developed around the practice of umbilical cord clamping. RhoGam introduced to prevent formation of maternal antigen to Rh factor. 1970s Early clamping of the cord was urged to prevent jaundice. 1980s Clamping the cord immediately after birth became part of the "standard of care." 1990s Umbilical cord blood banking became a for-profit business. 2000s "Delayed clamping" of the cord (for 30 secs to a minute or more) is advocated based on results of randomized controlled trials (RCTs).