Vitamin K Prophylaxis in Newborns and Bleeding in Infancy
Missing newborn vitamin K injection was linked to more infant bleeding.
*Nationwide cohort study; Level 2b (OCEBM).
Citation
Simatou E, Tsamantioti E, Hallström A, et al. Vitamin K Prophylaxis in Newborns and Bleeding in Infancy. JAMA Pediatrics. Published July 13, 2026. doi:10.1001/jamapediatrics.2026.2606
Background
Vitamin K deficiency bleeding is rare but can be life-threatening, especially when bleeding occurs in or around the brain. A single newborn vitamin K injection is standard care, but parental refusal has increased in several countries.
Patients
2,020,302 live-born infants in Sweden from 2003 to 2021, born at 35 or more weeks’ pregnancy. Exclusions included stillbirth, earlier gestation, missing key identifiers, likely documentation-error region-year data, and hemophilia.
Intervention
No documented vitamin K injection at birth.
Control
Documented vitamin K injection at birth.
Outcome
Any bleeding diagnosis by 6 months; secondary outcomes included bleeding in or around the brain and bleeding by 28 days.
Follow-up Period
6 months.
Results
Nonreceipt was uncommon but increased from 0.66% in 2006 to 1.50% in 2021.
| Outcome | No injection rate | Injection rate | Adjusted odds ratio (95% confidence interval) | Approximate extra harm |
|---|---|---|---|---|
| Any bleeding by 6 months | 636.1 per 100,000 | 379.6 per 100,000 | 1.52 (1.27-1.81) | 1 extra case per 390 missed injections |
| Brain bleeding by 6 months | 220.4 per 100,000 | 63.4 per 100,000 | 2.91 (2.13-3.96) | 1 extra case per 637 missed injections |
| Any bleeding by 28 days | 274.0 per 100,000 | 92.2 per 100,000 | 2.62 (1.99-3.44) | 1 extra case per 550 missed injections |
Among infants without an injection from 2012 to 2021, 9.9% received oral vitamin K. Oral vitamin K was also associated with higher bleeding odds than injection. The control was current standard care.
Limitations
Observational design prevents firm proof of causation. Vitamin K documentation may be incomplete or misclassified. Bleeding diagnoses were registry-based, not always confirmed as vitamin K deficiency bleeding. Breastfeeding, medication, and adherence to oral dosing were not fully measured.
Funding
Swedish foundations and public grants; no conflicts reported.
Clinical Application
Reinforces current practice: give newborn vitamin K injection and counsel hesitant parents early, especially before home birth or refusal decisions.
Discussion
Sign in to join the discussion.
In this nationwide cohort study, nonreceipt of intramuscular newborn vitamin K was associated with higher bleeding by 6 months (aOR 1.52; 636.1 vs 379.6 per 100,000). Given the observational design cannot prove causality, how should we judge validity, applicability, and whether to change counseling practice? In this cohort study, infants without documented intramuscular vitamin K had an adjusted odds ratio of 1.52 for any bleeding by 6 months, with rates of 636.1 vs 379.6 per 100,000 live births. Which interpretation is most appropriate?