Foto pixabay free. Charles Darwin, the grandson of Erasmus
Erasmus Darwin, physician, scientist (grandfather of Charles Darwin): "Another thing which is very injurious to the child is the too early tying and cutting of the umbilical cord. This should be refrained from not only until the child has breathed repeatedly, but until all pulsation in the umbilical cord ceases. Otherwise the child will be so much weaker than it should be, and accordingly a portion of the blood would remain in the placenta destined for the child.

"Zoonomia, 1801; Vol. III page 321
Darwin was one of the first physicians whose commitment to physiologically sound (natural) cord clamping is documented.