In the year In 2010, I published an article on this site about vitamin K prophylaxis for newborns. That article reflected the state of the legitimate scientific debate active at the time, centered on a 1992 study by Golding et al. published in the BMJ reported a possible association between intramuscular vitamin K and childhood leukemia.1
Sixteen years later, I owe an amendment, because science has moved decisively and my position on it has changed. This is how evidence-based medicine should work. As the data changes, so do the supported areas. Each reference in this article is retrieved from PubMed and can be individually verified by PMID number.
Why are newborns at risk?
Newborns have very limited stores of vitamin K. The vitamin does not cross the placenta efficiently, breast milk contains only small amounts, and the newborn’s gut does not have the bacterial population to help it produce it later.2,3
This creates a window of vulnerability during the first six months when a baby’s clotting ability is compromised.
Vitamin K deficiency bleeding, or VKDB, is divided into three types based on timing: Early VKDB occurs within 24 hours of birth and is typically associated with maternal medications. Classic VKDB occurs between days one and seven and is associated with delayed feeding. And late VKDB occurs between two weeks and six months – the most dangerous form because it often manifests as bleeding in the brain.4,5
Without any prophylaxis, late-onset VKDB occurs in approximately 5 to 80 per 100,000 live births, depending on the population.6 When seen as internal bleeding, the mortality rate ranges from 20% to 50%, and survivors often suffer permanent neurological damage.7
How effective is the vitamin K shot?
A very comprehensive systematic review on this topic was published by Sankar et al. In the year 2016 in the Journal of Perinatology. Pooling observational data from four countries, they found that a single intramuscular or subcutaneous dose of vitamin K during delivery reduced the risk of late VKDB by 98% – a pooled relative risk reduction of 0.02 (95% CI, 0.00-0.10).8
In a 2022 clinical report published in Pediatrics, the American Academy of Pediatrics reaffirmed its recommendation for universal vitamin K supplementation at birth.9 This advice has been consistent since 1961 – over six decades of clinical experience.
A 2026 review by Mirone et al. In the International Journal of Molecular Sciences, he provided a detailed molecular analysis of how vitamin K prophylaxis works and found that the muscle pathway provides complete protection against both classic and late-onset 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 used multidose oral protocols with partial success.
However, the evidence consistently shows that oral prophylaxis is less effective than injection in preventing late VKDB. Sankar et al. A single oral dose significantly increased the risk of late VKDB compared with vaccination (RR 24.5). Multiple oral doses performed better but still showed a nonsignificant trend toward higher risk (RR 3.64).11
A Dutch study by Lowenstein et al. (2019) showed that even a sixfold increase in oral vitamin K dose resulted in a modest reduction in intracranial VKDB. The authors concluded that undiagnosed cholestasis—a common liver disease in breastfed infants—prevents effective absorption of oral vitamin K, no matter how high the dose.12
In the year A Swiss intelligence study in 2026 confirmed this pattern. Over six years of follow-up of 505,708 births, every VKDB case involved either parental vitamin K deficiency, undiagnosed cholestasis, or both.13
In the year A 2025 review of Nutrition Reviews adds evidence that exclusively breastfed infants may be deficient in vitamin K even after vaccination at birth, providing support for continued supplementation in the first trimester.14
The risk of cancer has been put to rest
The most persistent fear about vitamin K comes from a 1992 case-control study by Golding et al., which reported a two-fold increased risk of childhood cancer with skeletal muscle vitamin K (OR 1.97; 95% CI, 1.3-3.0).15 This discovery sparked a wave of research. Four major population-based studies have examined the question, and the results are unanimous—no association:
• Ekelund et al. (1993) – 1.38 million children in Sweden. Cancer or: 1.01. Leukemia or: 0.90. There is no association.16
• Klebanoff et al. (1993) – 54,795 children, New England Journal of Medicine. Cancer or: 0.84. Leukemia or: 0.47.17
• According to Kries et al. (1996) – A population-based study in Germany. Leukemia OR: 0.98. There is no association.18
• Fear and others. (2003) – UK Childhood Cancer Study, 2,530 cancer cases, 4,487 controls. There is no connection with any childhood cancer.19
Broson and Klein reviewed this evidence in 1996 in the Journal of the Canadian Medical Association and concluded that there is no compelling reason to change standard practice.20 2026 Miron et al. A review confirmed this conclusion with three additional decades of data.21 The cancer question has been fixed. It should no longer be a factor in any parent’s decision about vitamin K.
The disturbing development in denial
Despite the clarity of the evidence, vitamin K rejection is on the rise. A 2026 JAMA study by Scott et al. The rate of newborns in the U.S. not getting vitamin K will rise from 2.92% in 2017 to 5.18% in 2024 among more than five million births.22
An international study published in Pediatric Blood and Cancer found that in high-income countries, parental rejection of intramuscular injections is the most common immune barrier.23
What happens when parents refuse? In the year A 2026 case report in Child Neurology described a two-month-old child who arrived at the emergency department with an unresponsive pupil with a blown pupil. A CT scan showed massive brain hemorrhage. His INR – blood clotting index – was over 15 (normal is around 1). He did not receive vitamin K at birth. He needed emergency surgery to remove part of his skull to relieve the pressure on his brain.24 survived. Many do not.
Shah, Brumberg, and La Gama In 2020, they published a review examining the similarities between vitamin K resistance and vaccine hesitancy, suggesting that both are driven by misinformation on social media and geographic clustering.25
Where I stand now
Based on the overall published evidence, I support vitamin K prophylaxis for all newborns. The way in the muscles provides the most reliable protection. The risk of cancer is definitely solved.
I recommend that every parent discuss vitamin K with their child’s pediatrician. If you’re not sure, the smart choice is to give it a shot. The risks of VKDB – brain hemorrhage, permanent damage, death – are real and well documented. The risk of the injection is negligible.
My understanding of this topic has evolved as the evidence has grown. This is how science is supposed to work. As the data changes, the data fields are changed with it. The facts are clear: Vitamin K saves lives.
Note to parents
If you are a parent researching this topic, I want to be straight with you. The internet contains a great deal of misinformation about vitamin K. Some may refer to my own 2010 article. This topic reflects the way in which scientific debate has been resolved. Science has moved on, and so have I.
Your pediatrician is your best resource for newborn care decisions. Vitamin K deficiency bleeding is rare, but when it does occur, the consequences can be devastating and irreversible. An injection during childbirth can prevent. Please contact your doctor.
