TOPLINE

The proportion of infants with undocumented intramuscular vitamin K administration at birth in Sweden decreased initially but increased from 0.66% in 2006 to 1.50% in 2021. Infants who did not receive this prophylaxis had increased odds of bleeding and intracranial hemorrhage within the first 6 months of life, with oral vitamin K also linked to an elevated risk for bleeding compared with intramuscular administration.

METHODOLOGY

• Researchers conducted a nationwide cohort study in Sweden that included more than 2 million live-born infants at ≥ 35 weeks’ gestation from 2003 to 2021.
• Exposure was defined as the nonreceipt of intramuscular vitamin K at birth based on checkbox documentation of the same in the mother’s delivery chart, transferred to the Swedish Medical Birth Register; data on oral vitamin K administration were available for births from 2012 onward.
• The primary outcome was any bleeding diagnosis within the first 6 months of life.
• The secondary outcome was intracranial bleeding within 6 months, with an additional evaluation conducted for bleeding diagnoses within the first 28 days after birth.

TAKEAWAY

• Overall, 1.19% of infants (mean gestational age, 40.0 weeks; 48.2% girls) had no record of intramuscular vitamin K administration at birth, with the proportion decreasing from 1.32% in 2003 to 0.66% in 2006 and then gradually increasing to 1.50% in 2021 (P for trend < .001). Among infants who did not receive intramuscular vitamin K, 9.9% received oral vitamin K.
• Infants who did not receive intramuscular vitamin K had higher odds of any bleeding diagnosis (adjusted odds ratio [aOR], 1.52; 95% CI, 1.27-1.81) and intracranial bleeding (aOR, 2.91; 95% CI, 2.13-3.96) during the first 6 months of life than those who received intramuscular vitamin K.
• During the first 28 days of life, infants who were not administered intramuscular vitamin K had increased odds of any bleeding diagnosis (aOR, 2.62; 95% CI, 1.99-3.44) and intracranial bleeding (aOR, 2.90; 95% CI, 2.08-4.05) compared with those who were administered intramuscular vitamin K.
• Infants who received oral vitamin K at birth had higher odds of any bleeding diagnosis within 6 months than infants who received intramuscular vitamin K (aOR, 2.26; 95% CI, 1.33-3.84).

IN PRACTICE

“[The] findings have important clinical implications, highlighting the ongoing need for communication between healthcare practitioners and parents about the vital role of vitamin K prophylaxis in preventing potentially life-threatening bleeding in newborns,” the authors of the study wrote. “These findings support the need for continued efforts to promote adherence to national guidelines and recommendations,” they added.

SOURCE

The study was led by Eleni Simatou, MD, Division of Clinical Epidemiology, Department of Medicine at Karolinska Institutet in Stockholm, Sweden. It was published online on July 13, 2026, in JAMA Pediatrics.

LIMITATIONS

Differences in electronic medical record systems across regions might have introduced some misclassifications. The study did not include information on socioeconomic factors or the distribution between rural and urban areas. The number of infants who received oral vitamin K was small, which might affect the applicability of the findings.

DISCLOSURES

The study was supported by H.R.H. Crown Princess Lovisa Society for Child Care, the Linnea and Josef Carlsson Foundation, the Swedish Medical Society, and the Ulla Hamberg Angeby and Lennart Angeby Foundation. Data extraction conducted in the study, as well as one of the authors, were supported by the Swedish Research Council, the Stockholm County Council, and ALF Medicine. Another author was supported by the Swedish Medical Society and a Region Stockholm clinical researcher appointment. No conflicts of interest were reported by the authors.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.