Why in news?
A US study published in JAMA Pediatrics on 5 November 2026 reported an increase in recorded vitamin K deficiency and associated bleeding among infants. Researchers examined health records covering about 11 million infants between 2017 and 2025. Receipt of injectable vitamin K fell from 97.7% to 95.0%, while the recorded rate of vitamin K–deficient bleeding rose by 347%. Vitamin K helps clotting proteins function, which explains its role in preventing serious bleeding in newborns.
How vitamin K supports clotting
Vitamin K is a fat-soluble vitamin. The body needs it for an enzyme that modifies certain proteins so they can perform their functions. These include clotting proteins such as prothrombin, also called clotting factor II. When blood vessels are injured, the clotting system helps form a stable clot that limits blood loss.
A deficiency can leave these proteins functioning inadequately. Bleeding caused by low vitamin K is called vitamin K deficiency bleeding (VKDB). In infants, bleeding can occur in the intestines, brain or other parts of the body. Internal bleeding can become serious before it is visible to a caregiver.
Why newborns have low stores
Only small amounts of vitamin K pass across the placenta during pregnancy. Breast milk also contains relatively little of it. A newborn therefore starts life with small stores, while the intestinal bacteria that can contribute vitamin K are still becoming established. These features create a period of particular vulnerability.
A preventive vitamin K injection supplies the nutrient after birth. This practice is called prophylaxis: an intervention given to prevent illness. The US Centers for Disease Control and Prevention recommends vitamin K at birth to protect against deficiency and the bleeding it can cause.
What the new study measured
The research examined infants from birth to six months who had been born at 35 weeks of pregnancy or later. It used existing electronic health records to compare vitamin K receipt and diagnoses across years. The analysis concerned infants represented in the participating health systems.
The original table records 189 VKDB diagnoses among 786,703 births in 2017 and 1,764 among 1,642,316 in 2025. These correspond to approximately 24 and 107 diagnoses per 100,000 recorded births. Comparing the rates accounts for the different annual sample sizes. The reported 347% rise is the relative increase in that diagnosis rate.
Dietary forms and absorption
Vitamin K1, or phylloquinone, occurs mainly in green leafy vegetables. Vitamin K2 covers a group of compounds called menaquinones. Several are present in fermented or animal-based foods, and gut bacteria also produce menaquinones.
Dietary vitamin K is absorbed in the small intestine through processes involving bile and pancreatic enzymes. Its fat-soluble character connects absorption with the digestion of dietary fats. The vitamin then travels through the body in lipid-carrying particles.
Vitamin K–dependent proteins also occur in bone. Osteocalcin is one example studied for its involvement in bone mineralisation and turnover. This broader biology helps explain why vitamin K appears in discussions of both blood clotting and bone metabolism.
Conclusion
The study draws attention to recorded trends in newborn preventive care and bleeding diagnoses. Understanding vitamin K’s role connects those findings with the biological reason for supplying it at birth: enabling clotting proteins to function during an infant’s early months.
Sources
- Wolf and colleagues, JAMA Pediatrics, 5 November 2026: vitamin K deficiency and associated bleeding in infants
- JAMA Network: study summary and observational design
- Virginia Commonwealth University release, 6 November 2026, distributed by Medical Xpress: study sample and findings
- US Centers for Disease Control and Prevention: newborn vitamin K, clotting and bleeding prevention
- US National Institutes of Health: vitamin K forms, absorption, clotting and bone proteins