Philadelphia – November 05, 2026 -- The share of US newborns not receiving the routine intramuscular vitamin K injection more than doubled between 2017 and 2025, rising from 3.1% to 6.8%, according to a Children's Hospital of Philadelphia (CHOP) study published in JAMA. It is the largest retrospective analysis of the trend to date, covering more than 5.2 million hospital births.
Infants without the injection showed a 47% higher risk of bleeding
Researchers analyzed deidentified electronic health record data from hospitals and clinics in all 50 states and Washington, D.C. The cohort included infants born at 35 to 43 weeks' gestation and followed them through their first six months of life. Of these, 234,825 infants (4.5%) did not receive intramuscular vitamin K at birth.
Recorded bleeding events reached 288 per 10,000 births among infants without documented administration, versus 186 per 10,000 among those who received the shot. After adjusting for gestational age, sex, maternal characteristics, insurance status and neighborhood-level measures, lack of documented administration was associated with a 47% higher risk of any recorded bleeding event.
Intracranial bleeding more than doubled in unprotected infants
Recorded intracranial bleeding occurred in 33 cases per 10,000 births among infants without documented vitamin K, compared with 13 per 10,000 among infants who received the injection. Co-author Kevin Dysart, MD, an attending neonatologist at CHOP, said death during the birth hospitalization in the presence of a bleeding diagnosis was also more common in the group without documented administration.
The team estimated that for roughly every 114 newborns who did not receive the injection, there would be one additional bleeding event in the first six months of life, compared with a similar group that did receive it.
Excess risk appeared in every year of the 2017-2025 study period
Bleeding risk rose for all babies over the study period. Lead author Kristan Scott, MD, MSHP, now an assistant professor at Emory University School of Medicine, said the excess risk among unprotected infants was "striking and present in every year of the study." Scott conducted the research as an NIH T-32 postdoctoral fellow at CHOP.
Newborns have naturally low vitamin K levels and may be unable to clot blood effectively. The injection prevents vitamin K deficiency bleeding (VKDB), a rare but potentially life-threatening disorder that can include intracranial hemorrhage. Co-author Heather H. Burris, MD, MPH, an attending neonatologist at CHOP, said the study is the first to document a nationwide decline in administration paired with rising bleeding risk.
The authors call for better understanding of why use is declining and for continued education so families understand the preventable bleeding risks. Funding came from a National Institutes of Health training grant (T32HD060550) and a National Institute of Child Health and Human Development grant (K23HD109426).