In June, 8.1% of U.S. newborns in a national health-record analysis did not have a documented vitamin K injection within a day of birth, up from 5.2% in January—a 57.4% increase in six months. The rise matters because babies who miss the routine shot face a well-established risk of internal bleeding during the first half-year of life, sometimes without visible warning.

The new Truveta analysis covered 1,026,375 infants born from January 2019 through June 2026 across participating U.S. health systems. It found that nonreceipt began climbing in 2023, accelerated in 2025 and reached its highest monthly level in the study period this June. Across the full seven-and-a-half years, 97% of newborns had a documented injection, so the standard remains dominant even as the recent change is unusually sharp.

The result requires an important qualification. The study measured whether administration appeared in an electronic record, not whether a parent explicitly refused it; missing documentation, transfers and other clinical circumstances can also produce a nonreceipt record. Still, a dozen pediatric specialists told Reuters that refusals are becoming a prominent concern, and hospitals and pediatric practices are changing procedures in response.

A Small Injection Prevents a Hidden Bleeding Risk

Vitamin K enables the liver to activate proteins needed for blood clotting. Newborns start with low stores because little of the vitamin crosses the placenta, their intestines do not yet contain mature vitamin-producing bacteria and breast milk supplies only small amounts. That biological gap persists until feeding and the developing gut provide a more reliable source several months after birth.

Vitamin K deficiency bleeding can appear early, during the first day; classically, during the first week; or late, from one week through six months. Late cases are especially dangerous because an infant may appear healthy before bleeding begins inside the brain or intestines. The CDC says 30% to 60% of late cases involve bleeding in the brain and that warning bleeds are rare.

The standard preventive measure is a single intramuscular injection after birth, which can be delayed for as long as six hours to allow uninterrupted bonding. The American Academy of Pediatrics recommends one milligram for infants weighing more than 1,500 grams and a weight-based dose for smaller premature infants. The AAP says the injection supplies some vitamin immediately while storing the remainder in the liver for gradual release.

The Increase Extends a Longer National Trend

The 2026 acceleration did not begin from a stable baseline. A peer-reviewed JAMA analysis of 5.1 million births at 403 hospitals found that the unadjusted proportion of newborns without intramuscular vitamin K rose from 2.92% in 2017 to 5.18% in 2024. After adjustment for patient and hospital characteristics, nonreceipt increased from 2.57% to 4.62% over the same period.

The newer Truveta data point in the same direction but should not be treated as a seamless extension of the JAMA series. The databases include different health systems, populations and inclusion rules, while Truveta counted administration on the birth date or following day. Its 8.1% June estimate is therefore best read as evidence of a sharp recent increase within that dataset, not as a precise national census of every U.S. birth.

The Truveta analysis also found differences by sex and maternal age. In June, 8.9% of girls and 7.3% of boys lacked documented administration; nonreceipt during the first half of 2026 was highest among babies born to mothers ages 40 to 49. Those patterns do not establish why families made a decision, and the researchers cautioned that hospital composition, documentation and local practices may contribute.

Girls Appear More Likely to Miss the Shot

A separate three-hospital study of more than 93,000 births in Pennsylvania found that parents were more likely to decline vitamin K and the hepatitis B vaccine for girls than boys. The authors proposed one possible mechanism: many hospitals will not circumcise a boy who has not received vitamin K because the procedure adds bleeding risk, potentially prompting some otherwise hesitant families to accept the injection.

That explanation remains a hypothesis, not a demonstrated cause. Circumcision preferences vary geographically and culturally, and administrative records do not capture the full reasoning behind family choices. The national Truveta pattern nevertheless strengthens the case for monitoring sex differences because the gap appeared across most years and widened as overall nonreceipt increased.

The difference also has a practical implication for surveillance. If circumcision policies indirectly raise acceptance among boys, girls may become a larger share of infants vulnerable to deficiency bleeding even though the underlying physiology is not sex specific. Clinicians would need outcome data, not only administration records, to determine whether that disparity is translating into more bleeding diagnoses.

Nonreceipt Is Not the Same as Harm

The latest U.S. analysis did not track bleeding after discharge, so it cannot show that the rise in nonreceipt has already caused more injuries or deaths. Its data were preliminary, had not undergone peer review and were current as of July 22. The dataset also cannot consistently distinguish refusal from incomplete documentation or a delayed injection recorded outside the delivery system.

The causal evidence for prophylaxis itself is much stronger. A nationwide Swedish cohort of more than two million births found that infants without recorded intramuscular vitamin K had higher adjusted odds of any bleeding and nearly three times the adjusted odds of intracranial bleeding during the first six months. Because it was observational, the study still cannot eliminate every difference between families who accepted and declined treatment, but its findings align with the known clotting mechanism.

U.S. case investigations show what the rare outcome can look like. In a 2013 Tennessee cluster, four previously healthy infants whose parents had declined vitamin K developed late deficiency bleeding at six to 15 weeks. Three had diffuse intracranial hemorrhage and one had gastrointestinal bleeding; all survived, although one child had an apparent gross motor deficit when the CDC reported the cases.

Mistrust Spills Across Newborn Care

Vitamin K is not a vaccine, but parents encounter it beside other routine interventions shortly after delivery, including hepatitis B vaccination and antibiotic eye ointment. Studies have repeatedly found that families who decline one are more likely to decline others. Published interviews identify concerns about ingredients, dosage, side effects and information encountered online, along with a preference for what families perceive as natural care.

Federal vaccine policy has added another layer of uncertainty. The increase in vitamin K nonreceipt predates the current administration, and the Truveta data cannot establish that any policy announcement caused the 2026 acceleration. Health officials told Reuters that mistrust grew through the COVID-19 period, while pediatricians said recent changes and conflicting public messages about newborn vaccines can spill over to the unrelated vitamin injection.

Some families ask for oral vitamin K instead of the shot, but the alternatives are not equivalent. Oral absorption is less consistent, multiple doses are needed and no oral product is approved in the United States specifically for newborn prophylaxis. A 2016 clinical review estimated that intramuscular administration reduces deficiency-bleeding risk from roughly one in 59 without prophylaxis to about one in 100,000.

The Next Test Is Whether Bleeding Cases Rise

Hospitals are responding at different points in care. Some require parents who decline the injection to sign a risk-acknowledgment form; others prohibit circumcision without prophylaxis, and pediatric groups have begun stocking vitamin K so families can reconsider after discharge. Those approaches may reduce harm, but they do not replace consistent national measurement of administration and subsequent bleeding.

The central surveillance challenge is linking birth records to outcomes through six months, including emergency visits at facilities outside the delivery system. HHS told Reuters that the department and CDC are evaluating available refusal and bleeding data. A reliable national signal will require separating genuine refusals from documentation failures, identifying where nonreceipt is concentrated and measuring whether intracranial or gastrointestinal bleeding changes afterward.

What the evidence establishes now is narrower but consequential: documented vitamin K nonreceipt has risen sharply in a large U.S. dataset after several years of broader increases, while the preventive benefit of the injection is supported by physiology, longstanding surveillance and large observational studies. The unanswered question is whether health systems can reverse that pattern before a preventable rise in catastrophic infant bleeding becomes visible in outcome data.