This isn't anything new.
We learned this 50 years ago when we were in our medical school.
Someone (probably an assistant professor whom I don't remember now) told us
that clamping the cord late will give more blood to the baby.
He actually said "how many more grams of blood" would be added to the baby.
I no longer remember the figure.
But, at that time, he mentioned that giving more blood to the baby might not be a good thing.
One of the reason was the neonatal jaundice... or something similar to this.

I was a student then. Somehow, it struck me and I vividly remember this talk ever since.
I always thought about this while clamping the umbilical cord
while I was rotating through Ob-Gyn service during my training.
However, I had never asked anyone on this subject.

It seemed that it was more important that we clamped and cut the cord ASAP,
and got the delivery finished and over with.
And, then, take the mask and gloves off for freedom !!

When a baby gets out of his (or her) mother, there are strong pulses in the umbilical cord,
and then within 30 second or 1-2 minute, the pulses disappear and the cord gets deflated.
Obviously, the blood is gone into the baby and the unbilical circulation gets terminated
by the order of our good Lord.
For whatever reason, every time, we hurry up to clamp the cord while it is pulsating,
cut it off and get the baby off the delivery table.
Hand the baby to the pediatrician if there's one, and then pay attention to the mother.
Get the placenta out and finish the deal.
(I am not an Ob-Gyn man. This was an observation by me, a trainee.) 

The moral of my story is:
It's not that doctors did not know about this amazing (?) fact,
they just want to get out of the delivery room ASAP.

PS: You won't see a story like mine anywhere else in the world.
Please keep it to yourself.

“What will sway A.C.O.G. are a couple of studies in progress showing a potential long-term neurological benefit,” Dr. Raju said.
 Improved iron stores in theory could help reduce the risk of learning deficiencies and
cognitive delay in children, which have been linked to iron-deficiency anemia in school-age children.
 
The above is the last paragraph of the above article.
And I see the potential lasting benefit for the baby by delaying the severance by at least one minute.
Thanks for the comment, WM.

산과 문제가 대두되고 논의된다는것이 한편 놀랍고 우리웹의 다양성을
말해주는것이라 생각합니다.

산과를 그만둔지가 벌서 12년이되어 최근정보에 어두운 문외한이 되었
지만 과거의 경험을 돌아보면 운영자님의 말씀대로 산과에서는 일종의
상식이지만 실제로 행하여지지 않는 이유를 생각해보면 대부분의 분만이
만삭분만이어서 큰영향을 볼수 없으며 또 산과의사의 입장에서는 분만시
다른 중요한 일들도 바로 해야되어 그런것인지 모르겠습니다.

다만 특정한 경우 예로 미숙아, 많은경우에 빈혈이 문제가 되는 경우에는
분만시 되도록 많은 수혈을 받는(어머니로부터)것이 바람직하여 많은경우에
cord clamping전에 cord를 태아쪽으로 두어번 훓터주어 일종의 수혈 역활을
시켜줍니다. 어떤경우에 This could be life saving manuver for the primi or
prevent lots of tests ending up blood trasfusion.  

물론 심장병이 의심되는 경우 태를 훓터 수혈시키는 것이 때로는 애의 심장에
over load가 될수 있으니  조심해서 결정할 문제 이겠지요.  규정