I read on multiple sites about how to help a queen give birth to her kittens, and almost all of them say that the cat usually chews the umbilical cord, but if she doesn't, then you have to do it. But instead of just snipping it, they want you to tie thread on either side of it. I am completely blind, and without some means to envision what is actually going on, it is very hard for me to imagine why using a thread would be necessary when I could simply feel between the kitten's body and end of the cord and snip in between.
Besides, if you tied the thread to either side of the cord and then snipped the cord, the thread (if not snipped) would hold the severed cord, and it might also pose a danger to the queen.
Here's an example of one of these articles.