I was just reading a post on Midwife Thinking's Blog that does a great job of explaining why I don't go in for cord blood banking. I know the usual reasons I've heard are that those stem cells could someday be used to treat that child's illness later on, or that they are an ethical source of stem cells to develop treatment for others.
The problem with the first reason is that the child may never have an illness where those stem cells could be helpful in treating him. Even if he does, there's no guarantee those stem cells will create a viable treatment for him. But it has been shown that allowing the baby to receive the full amount of his blood is beneficial. It's possible that blood, with those stem cells, could even help prevent any potential illness for which the stem cells would later be used to treat.
That leads me to the problem with the second reason. Is it truly ethical to deprive a newborn of his own blood in order to bank it either for his or another's future use, without his consent? Blood that makes Vitamin K deficiency bleeding less likely, raises his iron stores, and make his transition to breathing easier. I'm not so sure it's really ethical to do that, to be honest.
I will say that I thought about cord blood banking when I was pregnant with K. However, the more I looked into it, the more convinced I was that delayed cord clamping was the way to go, and that means cord blood banking isn't an option. Unfortunately they did not follow my wishes about the delayed cord clamping with K, but C received the full amount of her blood, since the cord was not cut until it stopped pulsating.