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Refusal of the newborn vitamin K shot in the US more than doubled from 2017 to 2025, from 3.1% to 6.8%. That is the finding of a study published Thursday in JAMA. A second paper in JAMA Pediatrics, found diagnosed vitamin K deficiency bleeding in infants rose 347% in that time.
The shot is a single injection into the thigh. The American Academy of Pediatrics has recommended it for every newborn since 1961. Neither study can prove that refusals caused the extra bleeding, and both say so. But they point the same way, and the bleeding they track can kill or leave lasting brain damage.
Two big health-record studies point the same way
Both teams used Cosmos, a research database built from the health records of hospitals that run Epic software. They asked different questions of it.
The JAMA study was led by Kristan Scott of Children’s Hospital of Philadelphia (CHOP). It followed 5,240,780 babies born at 35 weeks or later from 2017 through 2025. About 234,800 had no record of the shot.
Those infants had a 47% higher adjusted risk of any bleeding by six months. Their rate of bleeding inside the skull was 2.43 times higher: 33.0 cases per 10,000 babies, against 13.2.
They were also 2.69 times as likely to die with a bleeding diagnosis before leaving the hospital. The authors caution that this estimate rests on small numbers. Co-author Heather Burris, a CHOP neonatologist, told CIDRAP why it matters. “Our study is the first to document a nationwide decline in administration paired with increases in bleeding risks,” she said.
The JAMA Pediatrics letter comes from Elizabeth Wolf, Steven Woolf and colleagues at Virginia Commonwealth University. They counted 11,000,782 infants up to six months old. Shot receipt fell from 97.7% to 95.0%. Diagnosed vitamin K deficiency bleeding rose from 24.0 to 107.4 cases per 100,000 infants.
Only 19.2% of the babies with that diagnosis had a record of the shot. “The rate in 2025 was approximately double what it was in 2024,” Woolf told Reuters. NBC News published the Reuters report.
The climb has not stopped. Reuters, using Truveta records on more than 1 million US births, reported that refusals rose more than 57% from January to June 2026.
Why a newborn needs the extra vitamin K
The body uses vitamin K to make blood clot. Babies are born low on it, the CDC explains. Little crosses the placenta, and breast milk carries only small amounts. The gut bacteria that make it have not arrived yet.
Without enough, bleeding can start any time from the first day to six months after birth. The “late” form peaks at two to eight weeks. The CDC says 30% to 60% of those babies bleed inside the brain.
One shot prevents it. The AAP’s 2022 policy statement sets the dose at 1 milligram within six hours of birth. The CDC says that window can be used for bonding first.
Our table of the key figures:
| Measure | Figure | Source |
|---|---|---|
| Babies without the shot, 2017 | 3.1% | JAMA (Scott et al.) |
| Babies without the shot, 2025 | 6.8% | JAMA (Scott et al.) |
| Vitamin K deficiency bleeding, 2017 to 2025 | 24.0 to 107.4 per 100,000 infants | JAMA Pediatrics (Wolf et al.) |
| Brain bleeds by 6 months, no shot vs shot | 33.0 vs 13.2 per 10,000 | JAMA (Scott et al.) |
| Extra bleeding events | 1 for every 114 babies who miss the shot | JAMA (Scott et al.) |
| Risk of late bleeding without the shot | 81 times higher | CDC |
| Late bleeding with the shot | fewer than 1 in 100,000 infants | CDC |
Put the JAMA figures together and the gap is about 20 more brain bleeds for every 10,000 babies who skip the shot.
What parents who decline say worries them
Neither new paper surveyed parents. The clearest account of their reasons is older. A 2013 CDC report described four Tennessee babies with late bleeding, three of them in the brain. Their parents had feared a link to leukaemia or thought the shot unnecessary. Some wanted to limit exposure to “toxins.”
The same report found 3.4% of newborns went without the shot at one Nashville hospital, against 28% at birthing centres. The CDC answers those worries directly. A small 1990 English study suggested a cancer link, but the CDC says larger studies found no evidence for it. It adds that the preservative, benzyl alcohol, is present in amounts too small to be dangerous.
The researchers place the recent rise in a wider loss of trust. Wolf, in VCU’s release, drew the parallel herself: “Similar to the recent measles outbreaks, we are seeing the real-world implications of growing mistrust of doctors and public health professionals.”
The comparison fits. US measles cases this year have passed 4,500, double the 2025 total. New York has recorded its first measles death in 30 years.
Reuters also pointed to mixed signals from the Department of Health and Human Services. Its changes to childhood vaccine advice are on hold in court. An HHS spokesperson said the CDC still recommends the shot.
Oral drops are a weaker substitute
Some parents ask for vitamin K by mouth instead. Children’s Hospital of Philadelphia says there is no FDA-approved oral vitamin K for newborns in the US. Oral doses lower the risk of early bleeding, CHOP says. But “even repeated oral doses do not match the injection’s effectiveness.” The schedule also runs over several weeks, and doses get missed.
The VCU authors take a practical line. If refusals keep rising, they suggest oral vitamin K as a second-line, harm-reduction option. It is meant for families who will not accept the injection. That is a fallback for those families, not equal protection.
The limits, and the call for tracking
The JAMA authors list real caveats. Home and birth-centre births, where refusal has run highest, are largely missing. Oral doses given outside the hospital were not captured. Coded “bleeding” also includes conditions that vitamin K deficiency does not cause.
Bleeding rates rose in babies who did get the shot too, from 136.6 to 221.8 per 10,000. Part of the trend may reflect coding or other causes. The gap between the two groups is the stronger signal.
The CDC does not track refusals or bleeding cases nationally, Reuters reported. HHS would not say whether that will change.
Rep. Kim Schrier and Sen. Angela Alsobrooks asked the CDC in June to start counting these bleeding events. The two papers now give them national numbers to point to.