The researchers found that babies who had later cord cutting (after one minute) had higher hemoglobin levels 24-48 hours post-partum and they were less likely to have iron deficiency at 6 months, compared to the early cutting babies.
Changes in medical practice to not come easily. It took over 200 years for sailors and seafaring merchants to accept the fact that deadly scurvy could be prevented in sailors by just taking citrus fruit on board long voyages. Dr. Ignaz Semmelweis proved that hand disinfectant could prevent child bed fever (with a maternal mortality up to 35%) but his ideas were rejected by the medical community and he ended up dying in an insane asylum. Despite his publishing of a book that showed the death rate falling to under 1% if physicians would just wash, it was decades before his theories were adopted.
We shall see if delayed cord clamping becomes adopted practice in the United States. In nature, the mother animal (including humans without medical assist) have to severe the cord naturally and that certainly takes a bit of time. Maybe there is some selection advantage to that delay in the health of the baby.