Eleni Simatou, Eleni Tsamantioti, Anna Hallström, Olof Stephansson, Neda Razaz, Martina Persson, Jenny Bolk
5 min
Vitamin K deficiency bleeding (VKDB) is a rare but life-threatening condition in newborns that is effectively prevented by intramuscular vitamin K administration. Despite its proven efficacy, global reports indicate a rise in parental refusal of this prophylaxis. This study aimed to evaluate temporal trends in the nonreceipt of intramuscular vitamin K in Sweden and determine whether this nonreceipt is associated with an increased risk of bleeding diagnoses during the first six months of life.
Researchers conducted a nationwide cohort study using Swedish national registers, including the Medical Birth Register and the National Patient Register. The study followed over 2 million live-born infants (gestational age ≥35 weeks) born between 2003 and 2021. The primary exposure was the nonreceipt of intramuscular vitamin K at birth. The researchers used logistic regression to estimate adjusted odds ratios (aORs) for bleeding diagnoses, controlling for maternal and infant characteristics such as age, education, parity, and mode of delivery. Sensitivity analyses were performed to account for potential documentation errors and competing risks.
The study found that while the rate of nonreceipt of intramuscular vitamin K was initially low, it more than doubled over the study period, rising from 0.66% in 2006 to 1.50% in 2021. Infants who did not receive the intramuscular injection had 1.52 times higher odds of any bleeding diagnosis and 2.91 times higher odds of an intracranial bleeding episode within the first six months of life compared to those who received the prophylaxis. The findings remained robust across various sensitivity analyses, including those excluding potential outliers and infants with neonatal complications.
These results provide strong evidence that the protective effect of intramuscular vitamin K remains critical in modern obstetric care. The increasing trend of parental refusal, coupled with the observed rise in bleeding risks, highlights an urgent need for improved communication between healthcare providers and parents. The study suggests that current educational efforts regarding the safety and necessity of vitamin K prophylaxis may need to be strengthened to ensure informed decision-making and to prevent avoidable, life-threatening infant morbidity.
Importance: Vitamin K deficiency bleeding in infants is a rare but potentially life-threatening condition that is effectively prevented by newborn intramuscular vitamin K prophylaxis. Despite this, there are reports of increasing parental refusal of vitamin K prophylaxis globally. Objective: To evaluate temporal trends of prophylactic newborn vitamin K administration and its association with bleeding diagnoses during infancy. Design, Setting, and Participants: This was a nationwide cohort study of births between January 1, 2003, and December 31, 2021, followed up until 6 months of age. The study setting was in Sweden and included all live-born infants born at 35 or more weeks' gestation during the study period. Data analysis was performed from June 1 to December 19, 2025. Exposure: The exposure was nonreceipt of intramuscular vitamin K administration at birth. Main Outcomes and Measures: The primary outcome was a bleeding diagnosis within the first 6 months of life. Data from the Swedish Medical Birth Register was linked to multiple Swedish national registers. Logistic regression was used to estimate adjusted odds ratios (aORs) with 95% CIs. Results: Among 2 020 302 live births, 24 089 infants (mean [SD] gestational age, 40.0 [1.6] weeks; 12 472 male [51.8%]) had no record of intramuscular vitamin K administration at birth. The rate of nonreceipt decreased during the first study years from 1.32% (1242 of 94 214 newborns) in 2003 to 0.66% (667 of 100 429 newborns) in 2006, and then gradually increased and more than doubled to 1.50% (1619 of 107 915 newborns) in 2021. Infants without intramuscular vitamin K administration had 1.54-fold higher odds (aOR, 1.52; 95% CI,1.27-1.81) of bleeding and 3.18-fold higher odds (aOR, 2.91; 95% CI, 2.13-3.96) of an intracranial bleeding episode during infancy, compared with infants with intramuscular vitamin K. Conclusions and Relevance: This cohort study shows that the number of infants in Sweden who do not receive intramuscular vitamin K administration at birth to prevent bleeding episodes continues to be low but is increasing, and these infants have a significantly higher associated risk of bleeding episodes, including intracranial hemorrhages. These findings suggest the importance of intramuscular vitamin K administration in the newborn period to prevent bleeding episodes and the need for continued education of parents and caregivers on its significance.
Alex: What about the oral alternative? Some parents who refuse the injection will accept an oral dose — is that a viable fallback?
Sam: The data suggest it's less reliable than the injection. Infants who received oral Vitamin K still showed elevated odds of bleeding compared to the intramuscular group. The likely mechanism is adherence: the oral regimen requires repeated weekly dosing over months, whereas the injection is a single event at birth. Miss a dose, or run into absorption issues in a breastfed infant with subclinical fat malabsorption, and the protection degrades. The injection bypasses all of that — it's a one-time intervention that ensures adequate coagulation factor levels through the vulnerable early window.
Alex: So the failure mode for the oral route is essentially implementation, not pharmacology.
Sam: Exactly. The drug works. The problem is the real-world conditions under which it has to be delivered. That distinction matters for how you counsel hesitant families — offering oral as a simple equivalent undersells the compliance burden.
Alex: Where would a careful referee push back on these conclusions?
Sam: The primary constraint is the registry-based outcome definition. Without clinical adjudication or lab confirmation, the bleeding codes are a proxy — a broad one. You can't rule out that some diagnoses in the non-receipt group reflect underlying conditions that also drove the refusal decision, though the sensitivity analyses make that harder to sustain as the sole explanation.
Alex: And on the exposure side?
Sam: They can't fully characterize why parents refused. The specific informational drivers of hesitancy — whether it's injection aversion, misinformation about additives, or distrust of hospital protocols — are unmeasured. That matters for designing any intervention, because the study gives you the population-level evidence that this isn't a theoretical risk, but translating that into behavior change requires understanding the decision architecture, not just the statistics.
Alex: Which points directly to the practical implication.
Sam: Right. The near-term clinical takeaway is that prenatal counseling needs to be more targeted — addressing the specific concerns that lead to refusal rather than simply restating that the standard of care exists. And the finding on oral Vitamin K reinforces that offering it as a straightforward alternative, without communicating the adherence requirements, may create a false sense of equivalent protection.
Alex: It's a useful reminder that even the most established preventive interventions depend on sustained public trust to function at the population level. Thanks for listening to ResearchPod.