The following website is from Gentle Birth. They discuss Five Good Reason to Delay Clamping the cord (http://www.gentlebirth.org/archives/lateClamping.html).
The first reason is basically that is what nature intended. The second reason it gives the parents a chance to bond with the newborn, slows down the drill. The third reason is because it may cause unusual lesion in the brains of infants. The fourth reason is the problem with Rh negative mothers, it is advised to wait until the placenta is delivered. The last reason is because the baby is designed to have the blood at birth, scientist have discovered t-cells which have cancer fighting properties in these blood...we shouldn't wait until 30 years later to give the blood to that baby, but now...to build strong bodies.
Part of my birth plan is to delay the clamping of the cord. I already advised my midwife of the cord clamping. I gave them the birth plan. When I arrive at the hospital, they should be aware of all my requests, such as not asking me for my level of pain, not asking me whether or not I want my epidural, not asking me whether my baby should be circumcised, not administering Vitamin K shots, or hep B, or eye ointment. I wrote that I don't want pacifiers and bottles for my baby. I took care of everything I could possibly think of using other people's ideas of birth plans, and merging them into what I needed for myself.
At 30 weeks, waiting for the next few 70 days or so...to pass by smoothly and happily.