A new committee opinion from the American College of Obstetricians and Gynecologists (ACOG) now recommends delayed cord clamping for both term and preterm newborns. The previous recommendations (2012) recommended the practice only in preterm infants. At that time, research demonstrated a clear benefit only in preterm infants. Over the past few years, new research demonstrates a clear benefit in term newborns as well.
There have been two main concerns about delayed cord clamping: it may increase the risk of newborn jaundice, and it may cause problems with postpartum hemorrhage in the mother. Research shows that the increased risk of jaundice is small, and that it does not contribute to postpartum hemorrhage.
Delayed cord clamping should now be standard practice in all hospitals and birthing centers. I have not seen any recent research into the percentage of hospitals or obstetricians practicing delayed cord clamping. It is part of an broader package of changes in recent years of delivery room practices for the better.
Update: The guidelines were officially endorsed by the American Academy of Pediatrics in June, 2017.