Skipping Newborn Vitamin K Injection Raises Risk of Serious Bleeding, finds study
A Swedish cohort study has found that although few newborns miss intramuscular vitamin K at birth, the number is increasing. Infants who did not receive the injection had a significantly higher risk of bleeding complications, including intracranial hemorrhage. The findings reinforce the importance of routine intramuscular vitamin K administration at birth and continued education of parents and caregivers about its lifesaving benefits. The study was published in JAMA Pediatrics by Eleni S. and colleagues.
The research team conducted an analysis of medical files of all living infants who were born at 35 weeks of pregnancy or greater in the whole of Sweden in a span of decades spanning from January 1, 2003 to December 31, 2021. Statistical and data analysis for the large amount of data was done from June 1 to December 19, 2025, with the final validation going on until early 2026.
For following the health status of these babies up to the age of 6 months, scientists correlated the Swedish Medical Birth Register with several other health databases of the nation. The main exposure variable for this research was the lack of documented intramuscular vitamin K injections among infants, while the primary clinical outcome was any bleeding event diagnosed by a physician in infancy.
Key findings:
- The nation-wide surveillance system efficiently tracked the delivery history and analyzed the complete delivery information for 2,020,302 total deliveries of live births.
- In this multi-decadal cohort, there were 24,089 babies that did not have a documented history of having received vitamin K intramuscular prophylaxis in newborn period, with an average gestational age of 40.0 weeks and a standard deviation of 1.6 weeks.
- The incidence of the lack of administration declined in the earlier years, going from 1.32% (1,242/94,214 newborns) in 2003 to as low as 0.66% (667/100,429 newborns) in 2006.
- After the low incidence of 2006, the incidence of the lack of administration increased steadily for ten years ahead, more than doubled and peaked in 2021 (final year of study) at 1.50% (1,619/107,915 newborns).
- Babies that did not receive the injection had 1.54-fold increase in their odds of getting a diagnosis of infant bleeding compared to protected babies (aOR, 1.52; 95% CI, 1.27 to 1.81).
- The lack of administration of vitamin K prophylaxis resulted in an alarming 3.18-fold increase in the odds of getting a severe intracranial bleeding episode (aOR, 2.91; 95% CI, 2.13 to 3.96).
In conclusion, the results of the cohort study indicate that the frequency of infants in Sweden who do not undergo intramuscular vitamin K administration at birth in order to prevent bleeding episodes is still low but increasing and has a substantially higher risk of being associated with such bleeding episodes, which include intracranial hemorrhages. The results also emphasize the role of intramuscular vitamin K administration in preventing bleeding episodes in newborns as well as further educating parents about it.
Reference:
Simatou E, Tsamantioti E, Hallström A, et al. Vitamin K Prophylaxis in Newborns and Bleeding in Infancy. JAMA Pediatr. Published online July 13, 2026. doi:10.1001/jamapediatrics.2026.2606
