Exclusive: The percentage of parents and caregivers in the United States refusing a standard vitamin K shot for infants at birth has accelerated sharply this year, putting more newborns at risk of life-threatening bleeding episodes ↧ EXCLUSIVE: US refusals of crucial newborn vitamin spike, raising ri... The percentage of parents and caregivers in the United States refusing a standard vitamin K shot for infants at ​birth has accelerated sharply this year, an exclusive data analysis for Reuters found, putting more newborns at risk of life-threatening bleeding episodes.