What to do with the umbilical cord attached to kitten and after birth?

leave it alone don't touch the kittens (they are to fragile at birth I wouldn't touch them until they are at least a week old (unless its winter then I put them in a towel or something). Its a mother cat's nature to eat the umbilical cord and all the blood and other fluids because in the wild usually mother cats hunt, but if they have kittens they can't so they have to eat the fluids and umbilical cord.