More parents are refusing a shot typically given at birth to reduce the risk of infant bleeding, a study recently published in the Journal of the American Medical Association found.
An injection of vitamin K, which helps with blood clotting, within six hours of birth has been a standard practice in the U.S. since 1961.
Since babies are born with low levels of the vitamin, they are more prone to serious bleeding, especially in the brain and gastrointestinal tract, according to the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP).
Since implementing widespread use of the shot, the U.S. has seen a significant decrease in infant bleeds caused by vitamin K deficiency, according to the CDC. Increased hesitancy around vaccination, however, has led to an increasing number of parents opting out, especially after the COVID-19 pandemic and the increased public scepticism of pediatric preventive care that followed.
The latest study, "Trends in Vitamin K Administration Among Infants," was published in JAMA on Dec. 8. Using electronic medical record data, the study's authors reviewed more than 5 million births at over 40 hospitals across all 50 states between 2017 and 2024. The number of infants who did not receive the shot at birth rose from 2.92% in 2017 to 5.18% in 2024, according to the report. The largest acceleration occurred after 2020.
Parents refusing the shot often expressed concerns about injection pain, potential adverse effects and doubts that it's necessary, said the study. However, changes to acceptance rates began in 2019, the study noted, meaning COVID-19-related medical scepticism has not been the sole source of changing attitudes.
Since 1961, the AAP has recommended that a single shot of vitamin K be given at birth to protect against bleeding. All babies are born deficient in vitamin K, which is vital to blood clotting, and cannot form what are called clotting factors, or substances in the body that help stop bleeding naturally.
Vitamin K deficiency can cause serious, life-threatening bleeding in infants up to six months of age, according to the CDC. Normal sources of nutrition for newborns, including breast milk, do not contain enough vitamin K to make up for this deficiency in the early months of life.
A single shot given within hours of birth ensures babies have enough of the vital nutrient to handle any potential bleeding in the immediate future. According to the CDC, newborns who do not get a vitamin K shot are 81 times more likely to develop severe bleeding than those who do get the shot.
"Waiting to see if your baby needs a vitamin K shot may be too late," the CDC webpage says. "Babies can bleed into their intestines or brain, where parents can't see the bleeding to know that something is wrong. This can delay medical care and lead to serious and life-threatening consequences."