The normal biological process at birth is for the cord to be left alone until it has finished delivering blood to the baby.
This post, by the very thorough Kate Emerson, explains the biological importance of cord blood as part of a normal birth.
She also cautions against being hoodwinked by cord banking advertisements.
Birth is a normal biological process. The less we interfere, the better it is. For us, and for baby. This article, and the many others on the site, are worth reading if you are facing this issue.