He says physicians commonly do it 12 to 15 seconds after a hospital birth, when iron-rich blood and oxygen from the placenta are flowing into a newborn and before their systems are functioning independently. "There's a dramatic change in circulation that takes place at birth, and that doesn't take place in an instant," says [David Hutchon], who spe...

Don't rush to cut umbilical cord, doctor warns: Wait a few minutes before clamping, says U.K. obstetrician