[Cord clamping at birth - considerations for choosing the right time (author's transl)]

From the historical point of view, cord clamping has been performed in natural child birth some time after the fetus has been delivered and after the expulsion of the placenta. In 1877 already Hayem could show that in late cord clamping (LC) the concentration of erythrocytes in the newborn blood is elevated if compared to early clamping (EC) of the unbilical cord. It was concluded that is was a result of placental transfusion. The underlying mechanism of the placental transfusion is the hydrostatic pressure between the placenta and the fetus, supported by uterine contraction and the time of cord clamping after birth. Placental transfusion is diminished if cord clamping is performed in less than 180 sec and if the newborn baby is positioned 20 cm and more above the placental insertion. The newborn responds to placental transfusion with an increase of hemoglobin and hematocrit, an elevated blood pressure, although significant differences in cardiac output could not be established. Renal function is increased and effective renal blood flow associated with the blood volume of the newborn. In cases of caesarean section a higher incidence of respiratory distress occurs if placental transfusion does not take place. In utero placental transfusion occurs if the fetus is hypoxic obviously to increase the oxygen supply to the fetal tissue.

"In order to give the newborn the blood, that it need physiologically cord clamping should be performed not immediately after birth, but one should wait as long until the umbilical vein has been empty and is collapsed." (Bumm 1902).