Infant bleeding rose as fewer newborns received vitamin K shots, according to two studies published Nov. 5. One analysis found a 347% increase in diagnosed vitamin K deficiency bleeding between 2017 and 2025. The findings raise concerns about the consequences of declining use of a treatment that protects newborns from potentially fatal bleeding.

Vitamin K shots decline as bleeding diagnoses rise

Researchers at Virginia Commonwealth University examined records covering more than 11 million infants in a study published in JAMA Pediatrics. The recorded rate of vitamin K deficiency bleeding climbed from 24 to approximately 107 cases per 100,000 infants. Meanwhile, the percentage receiving injectable vitamin K fell from 97.7% to 95%.

The increase accelerated in 2025. Researchers identified 1,764 affected infants that year, compared with 903 in 2024, although the study population also expanded. Accounting for that growth, the rate rose approximately 82% in one year. These figures describe diagnoses in participating health systems, rather than a complete national count.

Higher bleeding risk without vitamin K shots

A separate JAMA study led by Children’s Hospital of Philadelphia researchers analyzed 5.2 million infants. The share without documented vitamin K injections more than doubled, from 3.1% in 2017 to 6.8% in 2025. Those infants had a 47% higher adjusted risk of recorded bleeding within six months.

That finding covered several types of bleeding, not solely vitamin K deficiency bleeding. Across the study, approximately 288 of every 10,000 infants without documented injections experienced bleeding, compared with 186 who received them. Researchers also found more than twice the adjusted risk of bleeding inside the skull.

“The difference was particularly concerning for bleeding in or around the brain, a potentially life-threatening complication,” said study co-author Dr. Kevin Dysart. In the hospital’s announcement, he highlighted the difference in recorded intracranial bleeding. The rates were approximately 33 cases per 10,000 infants without the injection and 13 among those who received it.

Researchers point to growing mistrust

Vitamin K is a vitamin, not a vaccine. Nevertheless, Children’s Hospital of Philadelphia’s Vaccine Education Center has warned that concerns about newborn hepatitis B vaccination have spread to vitamin K. The VCU researchers also identified declining trust in public health and unease about newborn interventions as possible contributors.

Those concerns overlap with the broader debate over childhood vaccine recommendations. However, the new studies do not establish how much any particular message or policy influenced parents’ decisions. Researchers say understanding those decisions will require further work.

Dr. Elizabeth Wolf, the VCU study’s lead author, called for better communication in a university announcement. She said researchers need to understand why parents decline the injection and how to improve its acceptance. “We need clear messaging from all levels of public health about the benefits of vitamin K administration for newborns,” Wolf said.

What the studies can establish

Both studies used electronic health records from Epic’s Cosmos database, with different inclusion criteria and potentially overlapping populations. They were observational studies, so the findings cannot prove that parental refusal caused the entire increase. A missing medication record also does not establish why an infant lacked a documented injection.

The CHOP-led study found that bleeding increased among infants with and without documented vitamin K administration. The reason for that broader increase remains uncertain. Potential limitations include incomplete records, diagnostic coding errors and differences between infants that statistical adjustments may not fully capture.

How vitamin K shots protect newborns

Newborns naturally have little vitamin K, which the body needs to produce proteins involved in blood clotting. Only small amounts cross the placenta, and breast milk contains little of the vitamin. Without adequate protection, infants can bleed internally, including into the brain or intestines, before parents recognize a problem.

The American Academy of Pediatrics has recommended the birth injection since 1961. The CDC identifies it as the best way to prevent vitamin K deficiency bleeding, which can affect otherwise healthy infants. The danger can extend through the first six months of life, beyond the initial hospital stay.

Under CDC guidance reflecting the pediatric academy’s recommendation, newborns should receive the injection within six hours of birth. That window allows time for initial feeding and bonding. The recommendation applies to both breastfed and formula-fed infants, and clinicians should discuss bleeding risks with parents considering declining the shot.