In 2010, I published an article on this site about vitamin K prevention in newborns. The article reflected the state of the then-active legitimate scientific debate, centered on a 1992 study by Golding et al. A study published in BMJ reported a link between intramuscular vitamin K and childhood leukemia.1
16 years later, I need to give you an update. Because science has made decisive advances and my position has changed accordingly. This is how evidence-based medicine works. As data changes, the position from which the information is received changes. All references in this article were searched in PubMed and can be independently verified by PMID number.
Why Newborns Are Vulnerable
Newborns arrive with very limited vitamin K reserves. The vitamin does not cross the placenta efficiently, breast milk contains only trace amounts, and the newborn gut ultimately lacks the bacterial population that helps produce the vitamin.2,3
This creates a vulnerability during the first six months of life that reduces the infant’s ability to form blood clots.
Vitamin K deficiency bleeding (VKDB) is classified into three types depending on its timing: Early VKDB occurs within 24 hours of birth and is usually associated with maternal medications. Classic VKDB occurs between days 1 and 7 and is associated with delayed feeding. Late VKDB occurs between 2 weeks and 6 months of age. This is the most dangerous form because it often manifests as bleeding inside the brain.4,5
Without any form of prevention, late-stage VKDB occurs in approximately 5 to 80 people per 100,000, depending on the population.6 When intracranial hemorrhage occurs, the mortality rate is 20-50%, and survivors often suffer permanent neurological damage.7
How effective are vitamin K injections?
The most comprehensive and systematic review on this topic was published by Sankar et al. It was published in the Journal of Perinatology in 2016. Pooling surveillance data from four countries showed that a single intramuscular or subcutaneous dose of vitamin K at birth reduced the risk of later VKDB by approximately 98%. That is, the pooled relative risk is 0.02 (95% CI, 0.00-0.10).8
The American Academy of Pediatrics reaffirmed its recommendation for universal intramuscular vitamin K at birth in a 2022 clinical report published in Pediatrics.9 This recommendation has remained consistent through over 60 years of clinical experience since 1961.
A 2026 review by Mirone et al. The International Journal of Molecular Sciences provides a detailed molecular analysis of how vitamin K prophylaxis works and confirms that the intramuscular route provides almost complete protection against both classic and late VKDB.10
What about oral vitamin K?
Some parents prefer oral vitamin K because it avoids injections. Several European countries, including Switzerland and the Netherlands, have had partial success using multiple-dose oral protocols.
However, evidence has consistently shown that oral prophylaxis is inferior to injection for preventing late-stage VKDB. Sankar et al. A single oral dose was shown to dramatically increase the risk of late VKDB compared to injection (RR 24.5). Multiple oral doses performed better, but still had a non-significant trend toward increased risk (RR 3.64).11
A Dutch study by Löwensteyn et al. (2019) showed that a six-fold increase in oral vitamin K dose only slightly reduced intracranial VKDB. The authors concluded that undetected cholestasis, a common liver disease in breastfed infants, prevents effective absorption of oral vitamin K, regardless of dose.12
A 2026 Swiss surveillance study confirmed this pattern. After monitoring 505,708 births over 6 years, all VKDB cases involved parental vitamin K rejection, unrecognized cholestasis, or both.13
A 2025 review in Nutrition Reviews adds prospective evidence that exclusively breastfed infants can develop vitamin K deficiency even after receiving a shot at birth, supporting the case for continued supplementation during the first three months.14
Cancer concerns have been put to rest
The most persistent fear about vitamin K comes from a 1992 case-control study by Golding et al. This study reported a nearly two-fold increased risk of childhood cancer after intramuscular vitamin K administration (OR 1.97; 95% CI, 1.3-3.0).15 This discovery sparked a wave of research. Four major population-based studies examined this issue and came to unanimous conclusions. In other words, there was no correlation.
• Ekelund et al. (1993) — There are 1.38 million infants in Sweden. Cancer or: 1.01. Leukemia OR: 0.90. There is no connection.16
• Klebanoff et al. (1993) — 54,795 children published in the New England Journal of Medicine. Cancer or: 0.84. Leukemia OR: 0.47.17
• Kries et al. (1996) —Population-based study in Germany. Leukemia OR: 0.98. There is no connection.18
• Fear et al. (2003) — British Childhood Cancer Study, 2,530 cancer cases, 4,487 controls. It is not related to childhood cancer.19
Brousson and Klein reviewed this evidence in the Canadian Medical Association Journal in 1996 and concluded that there was no compelling reason to change standard practice.20 2026 Mirone et al. The review confirmed this conclusion with an additional 30 years of data.21 Cancer problem solved. It should no longer be a factor in parents’ decisions about vitamin K.
A troubling increase in rejection
Despite the clarity of the evidence, vitamin K denial is increasing. A 2026 JAMA study by Scott et al. Across more than 5 million births, the proportion of U.S. newborns not receiving vitamin K increased from 2.92% in 2017 to 5.18% in 2024.22
An international survey published in Pediatric Blood & Cancer found that parental refusal to receive intramuscular injections was the most common barrier to prevention in high-income countries.23
What happens if parents say no? A 2026 case report from the Child’s Nervous System describes a 2-month-old baby who arrived in the emergency room unresponsive and with dilated pupils. A CT scan revealed a massive brain hemorrhage. His INR (blood clotting degree) was greater than 15 (normal is around 1). He did not receive vitamin K at birth. He had to undergo emergency surgery to remove part of his skull to relieve pressure on his brain.24 He survived. Many people don’t.
Shah, Brumberg, and La Gamma published a review in 2020 that looked at the similarities between vitamin K hesitancy and vaccine hesitancy, noting that both are driven by misinformation on social media and geographic clustering.25
where i stand now
Based on all of the publicly available evidence, I support vitamin K prophylaxis in all newborns. The intramuscular route provides the most reliable protection. My cancer concerns have definitely been resolved.
I encourage all parents to discuss vitamin K with their child’s pediatrician. When in doubt, the prudent option is to give it a chance. The risks of VKDB (brain hemorrhage, permanent damage, death) are real and well-documented. The risks of injections are negligible.
As evidence grows, so does my understanding of this topic. That’s how science works. As your data changes, your informed position changes with it. The data is clear. Vitamin K saves lives.
A word to parents
If you are a parent researching this topic, I would like to speak directly to you. The Internet contains a significant amount of misinformation about vitamin K. Some of them may have referenced an article I wrote in 2010. The article reflected the state of the scientific debate, which has since been resolved. Science has advanced, and so have I.
Your pediatrician is your best resource for newborn care decisions. Vitamin K deficiency bleeding is rare, but when it occurs, the consequences are devastating and irreversible. One injection at birth can prevent this. Consult your doctor.
