In August, news emerged from Vanderbilt University that four cases of a rare bleeding condition seen in young infants had been diagnosed since February. Three of these infants suffered intracranial hemorrhages, requiring surgical intervention to evacuate the blood and save their lives, although there will almost certainly be neurological and developmental repercussions down the road. The fourth child presented with gastrointestinal bleeding and also survived. The parents of all four babies had refused an extremely safe and effective intervention on the day that they were born, one recommended by pediatricians since the early 1960’s, that would have prevented these outcomes.

When a baby is born, there are a number of rituals that parents and medical professionals take part in. Some are largely ceremonial, more rites of passage than anything medically necessary, such as the first bath or the assignment of APGAR scores. As a physician, I play my part in some of these rituals, the baby’s first exam being the most important. Unlike many medical examinations that pediatricians perform, the newborn exam involves a good deal of showmanship. It’s the only exam where I make a point of talking through each aspect with the parents, showing them all the normal but sometimes surprising (at least to new parents) things that babies do and common physical exam findings that many folks don’t know about and might lead to unnecessary concern. Really hammering home how healthy a new baby is can go a long way towards relieving parental anxiety. And anticipating and addressing common newborn issues during the exam helps save me a lot of time on the back end as well.

Nursing plays the largest role in the rituals of caring for a newborn baby. They give the first bath, change the first dirty diapers and typically assist with the first latch if a mom is breastfeeding. They perform common procedures, such as heel sticks for newborn screening and jaundice assessments if necessary. They really do a lot, providing a great deal of vital education for parents while doing it, and their role in the care of the newborn far outshines my contribution for the majority of healthy babies.

Another ritual that nursing plays a major role in, and one that has significant medical benefits associated with it, are vitamin K injections. But before I discuss why it is so important for newborns, especially those that are going to be primarily breastfed, to receive these injections, a little primer on vitamin K is in order.

What is vitamin K?

Vitamins in general are organic substances that are necessary for normal metabolic processes that cannot be made by the human body. We have to take vitamins in by eating foods that contain them. The beginning of our understanding of vitamin K goes back to 1929 when Danish researcher Henrik Dam discovered that a substance existed which could help correct bleeding induced by restricting cholesterol from the diet of chickens. This substance, named Koagulationsvitamin in the German journal that first reported the findings, has since been known as vitamin K. The fat soluble vitamin K was first isolated from alfalfa sprouts only a year later.

There are two main forms of vitamin K. We take in vitamin K1 when we eat leafy green vegetables like kale and spinach, but it is also found in broccoli. Because it plays a major role in photosynthesis, it isn’t found in root vegetables in large amounts. Vitamin K2 can also be obtained from the diet, usually in the form of aged cheeses, fermented vegetables and organ meats. Much of the vitamin K2 in our bodies is actually synthesized by bacteria in our intestines and then absorbed. In general, vitamin K1 is the most active form.

In order to absorb vitamin K, we need a functioning pancreas and biliary system. The vitamin K that we take in is bound to proteins that require pancreatic enzymes in the small intestine to be broken down. Bile salts then render the liberated vitamin K able to be absorbed into intestinal cells for processing and transport to the liver. So biliary and pancreatic disease can increase the risk of deficiency, which is actually quite rare in adults. Babies, now that’s a different story as I’ll soon explain.

What does vitamin K do?

The primary role of vitamin K in the human body is blood clotting. It is also involved in bone growth and density, but at this time there isn’t great evidence that supplementation is particularly helpful in preventing osteoporosis or fractures. In some countries, however, various formulations of vitamin K have been recommended for just that purpose. There is ongoing research into vitamin K’s role in the development of Alzheimer’s disease, heart disease and even some cancers, but these are hypothetical and may not pan out.

Vitamin K is a cofactor necessary for a number of key enzymes involved in clotting to work properly. In particular, clotting factors VII, IX, X and prothrombin produced in the liver require vitamin K-fueled activation. Without enough vitamin K, ultimately these proteins will not be attracted to circulating platelets and blood clotting will be impaired, which can lead to life-threatening bleeding complications. The medication warfarin takes advantage of this by blocking the conversion of inactive precursors into active vitamin K. This is why patients on warfarin are warned to avoid excessive dietary vitamin K intake as that may reverse the anti-clotting effects.

Why do babies need vitamin K shots?

Newborn infants are considered to be universally deficient in vitamin K. This happens for a variety of reasons. There is poor transfer of vitamin K across the placenta and the immature liver has both decreased storage capability and is inefficient at using available vitamin K. Naturally, this is even more pronounced in premature infants. Adding to this, breast milk does not contain sufficient amounts of vitamin K and the initially-sterile gut of the newborn does not significantly contribute to vitamin K levels in the body for several weeks.

There isn’t anything a mother can do about these etiologic factors. But some things can add to the risk even further. There are a number of medications, in particular warfarin and some anti-seizure drugs, that when taken by a mother during pregnancy increase the risk of vitamin K deficiency and bleeding complications in the new baby. Certain antibiotics used to treat tuberculosis can have a negative impact as well.

Without supplementation, newborns are at risk for a potentially devastating condition known as vitamin K-deficient bleeding (VKDB), formerly known as hemorrhagic disease of the newborn. VKDB is a better designation because life-threatening bleeds can occur as late as 3 months of age, particularly in breastfed babies who did not receive an intramuscular dose of vitamin K on the first day of life. Most bleeding occurs during the first week, however.

The really scary thing about VKDB is that it occurs in perfectly healthy babies and it happens spontaneously, not because they were dropped on their head for instance. Bleeding can present in many ways, ranging from mild to fatal. Skin bruising, bleeding into mucosal tissues (mouth, nose, throat, intestine, uterus, urethra), bleeding at the umbilical stump or circumcision site, and bleeding into the brain can all happen.

One of the most common presentations of easy bleeding in newborns is something called a cephalohematoma. These are bleeds under the periosteum, a dense connective tissue membrane that covers bone, and typically involve the parietal bones of the skull because of pressure to the scalp during even uneventful deliveries. Because the blood is trapped under the periosteum, these present as immobile but squishy (think silly putty) scalp masses, sometimes shockingly large, that can take weeks to resolve. Large cephalohematomas are a major risk factor for severe jaundice.

Without supplementation, as many as 1.7% of babies would be expected to have some kind of bleeding complication during the first week. This is known as “early VKDB” or classic hemorrhagic disease of the newborn, and it can be easily prevented by an intramuscular vitamin K injection on day one of life. It can also be prevented with oral supplementation. The evidence to support the efficacy and safety of these interventions is rock solid, but there are problems with oral supplementation when it comes to bleeding after the first week.

When there is a bleeding complication from vitamin K deficiency that occurs between 2 and 12 weeks of life, this is called “late VKDB.” This happens almost exclusively in babies fed primarily breast milk who did not receive adequate vitamin K prophylaxis, or who have some other major risk factor such as liver disease or cystic fibrosis. Late VKDB, as it did in the children treated at Vanderbilt Children’s Hospital, where I completed my pediatric training and a fantastic facility by the way, tends to present as unexpected bleeding into the brain.

The risk of late VKDB is felt to be around 4.4 to 7.2 per 100,000 children not receiving vitamin K prophylaxis. Oral vitamin K given on day one of life does not substantially reduce the risk, while intramuscular dosing renders it virtually nonexistent barring some other significant risk factor. Some countries promote longer-term oral vitamin K prophylaxis, and there are a variety of approaches. One common method is to dose vitamin K orally with the first feed and again at one, four and eight weeks of age. In the Netherlands, small daily doses have been recommended. While not every approach to oral prophylaxis has been extensively studied, such as the small daily dose regimen, many have been and it appears that there remains a risk of about 1-2 cases of late VKDB per 100,000 births.

Why would oral prophylaxis not work? There are just too many variables. Adherence to the recommended regimen may be poor for a variety of reasons. A child may be ill and vomiting, or on antibiotics which interfere with gut production by killing off intestinal flora. A family may simply forget. The amount of vitamin K in the breast milk may be affected by external factors as well. So while oral vitamin K may be cheaper and does not cause any procedural discomfort, and it may be better than none at all, the evidence supports intramuscular prophylaxis, especially when you consider the potential outcomes of late VKDB. Some countries that switched to oral regimens have seen spikes in the incidence of late VKDB, and Australia switched back to intramuscular. Of note, premature infants must receive intramuscular dosing because of poor absorption of oral formulations. Also, liquid oral vitamin K is not available in the United States.

Why would a family refuse vitamin K?

I imagine that regular readers of SBM are not surprised by the fact that vitamin K prophylaxis refusal is something that pediatricians and family practice doctors deal with, although not as frequently as vaccine refusal. Why do parents do it? Why would a parent reject an intervention that is so effective at preventing such a devastating consequence as bleeding into the brain of their baby and a potential lifetime of seizures, developmental delay and cognitive impairment? And one that is virtually risk free to boot!

Many families who refuse simply have a world view where medical intervention is perceived as unnatural. Many of these children are born at home or in birthing centers attended by midwives and doulas. They tend to have extensive and demanding birth plans when they deliver in the hospital and frequently also refuse antibiotic prophylaxis against neonatal conjunctivitis, another newborn ritual with less controversy attached to it. Eye and vitamin K prophylaxis are collectively referred to in nurseries as the “eyes and thighs”. These families also typically refuse the newborn hepatitis B immunization, perhaps a topic for another post, and go on to refuse or spread out childhood immunizations in the future.

Though not as widespread as anti-vaccine propaganda, and certainly lacking that particular entity’s infrastructure and celebrity support, there is an online presence of bogus anti-vitamin K information to be found. Naturally the chiropractic community is all over the place about this topic as they are with everything else. This particular practice warns that synthetic intramuscular vitamin K might cause cancer, kill your baby, or make them sterile, and questions the need for prophylaxis at all.

In March of 2010, our friend Dr. Mercola interviewed biochemist Cees Vermeer, who appears to be an expert on vitamin K who is involved in research to find new commercial applications, and published an article on the subject of newborn vitamin K prophylaxis that questions the mainstream approach. I also found several message boards and mommy groups citing this information as a reason to question the intramuscular injections. I’ll start off with what the article gets right. He appears to appreciate the need for vitamin K in newborns, and discusses some of the risks of deficiency. He is absolutely right when he says that newborns can feel pain, and that pain in the neonatal period can sometimes have long lasting effects. He is right when he says that oral vitamin K prophylaxis can be effective. Maybe I’ve been too hard on this guy.

I was shocked to find that Mercola even agrees with mainstream science that intramuscular vitamin K prophylaxis does not cause cancer. Because of some small, poorly done studies in the early 1990’s there was a brief period of concern that vitamin K prophylaxis increased the likelihood of pediatric leukemia. The question was thoroughly addressed by better studies and is not considered a problem. However it does occasionally come up as a reason to refuse, or as something that parents are worried about and want to discuss. For more information on this non-controversy, here is the AAP policy statement.

So now let’s tackle what Mercola gets wrong. I’m not sure how much of this represents his versus Vermeer’s understanding of VKDB, but they don’t appear to have a good understanding of it. He makes some pretty glaring mistakes (I’m being generous) in the article that are easily addressed. First off, he doesn’t seem to understand the differences between early and late VKDB. He mentions the risk of up to 1.7%, but not that this specifically is for the early form. He then declares that this is rare. I do not consider almost 2 out of every 100 births to be rare. The incidence of late VKDB is considerably lower and could reasonably be thought of as rare, but when it happens it usually results in a messed up brain. If nearly 2 out of 100 kids had brain bleeds, that would be horrific!

He states that there was no evidence to support the standard of care in regards to vitamin K prophylaxis when it was first implemented. Vitamin K became a routine standard of practice in 1961. I was able to easily find numerous papers going back a decade before that investigating the use of vitamin K prophylaxis in newborns. He likens what we do to a “shotgun approach” that was convenient. You know what is inconvenient? Brain bleeds.

He blames increased rates of circumcision on the push to give intramuscular vitamin K injections. This is absurd. It has been known for decades that oral prophylaxis is just as effective as intramuscular for early VKDB. Most circumcisions take place on day 2 or 3 of life. Intramuscular injections are recommended only because they work better than oral regimens for preventing bleeding complications in the 2nd to 12th week of life.

So why is Mercola so worked up about vitamin K? He just cares too much, I suppose, and can’t bear to think that newborn babies might be suffering from the pain of an intramuscular injection. Anyone who read my last post on pediatric pain should know how much I hate poorly managed pain, but even I think his concerns are over the top. Mercola likens the discomfort from an IM injection of vitamin K to psycho-emotional damage and trauma that causes an “emotional wound that the helpless and innocent baby needs to overcome to achieve health and wellness.”

Poorly managed pain in the neonate does have potential downstream repercussions. I really do need to go into more detail in a post on the subject. But to compare a one-time IM injection to a 25-week-premature infant riding a vent without appropriate pain control for 5 weeks, or twenty heel sticks over the first few days of life to follow blood sugars in the growth-restricted infant of a diabetic mother, is more than a little ridiculous. Untreated bouts of acute pain in neonates, such as a circumcision without any local anesthesia or sugar water, may increase their pain/stress response to future painful events in infancy such as routine childhood immunizations, but they do not “remember it” or have psychological problems further down the road. Infants who suffer chronic pain, usually premature babies that require mechanical ventilation and/or surgery, have actually been shown to have a blunted pain response. We don’t have good data on longer term issues regarding chronic pain in babies.

Mercola raises concerns about the safety of the dose of intramuscular vitamin K, stating that it is 20,000 times the needed dose. His source is “” Even if true (the needed dose for what?), he acts as if it is being injected straight into a vein. It is an intramuscular injection. The vitamin K is slowly metered out similar to penicillin shots that we give in place of lengthy courses of oral antibiotics for strep throat or the prevention of rheumatic heart disease flares. He worries about toxic preservatives injuring the baby’s immune system but gives no evidence to support this because there is none.

He mentions that an injection is an infection risk because the baby has an immature immune system and hospital bugs are so dangerous. This is theoretically true but the risk would be considerably lower than the risk of bleeding in a child not appropriately prophylaxed against VKDB, and he cites no data to support his concern. Intramuscular injections do have real risks, but they are very minor. A bruise or treatable local infection, for instance, must be weighed against the risk of a brain bleed.

Mercola recommends oral vitamin K as an equally effective alternative to the intramuscular dose. He says it is absorbed efficiently enough and there is no risk of overdosing or a bad reaction. He claims that oral dosing is even equivalent in exclusively breastfed babies, which is potentially very dangerous advice, but then says that future research is needed to find better “pinpoint guidelines.” Well, we have current research that says most oral regimens are less effective and we lack evidence to show that daily dosing is as effective as intramuscular injections for preventing late VKDB. If future evidence shows daily dosing to work as well as injections, then it may be a reasonable approach in some infants. But to completely ignore the fact that giving a medicine orally to a baby for long periods of time is prone to adherence issues shows his lack of any true understanding of this topic or of babies.

He quotes Vermeer as saying that if breastfeeding women just eat enough foods rich in vitamin K, their babies don’t need the intramuscular injection or the oral supplementation. Levels of vitamin K in breast milk are low, much lower than in infant formula, and it is not clear at all if dietary modification is good enough. And if a mother goes on a course of antibiotics, for instance, or is ill and unable to eat a diet high in green leafy vegetables for a period of time, her vitamin K levels may decrease and put the baby at risk for a bleed. Vermeer is a biochemist, not a physician and I would ignore his advice on the matter. I would ignore what Mercola has to say about this and everything else.


Newborn babies are amazing things. I don’t pretend to know everything there is to know about them, and I certainly don’t understand the evolutionary underpinnings of vitamin K deficiency in newborns. I guess it is uncommon enough that there was no pressure to evolve better transport of vitamin K across the placenta or to increase levels of vitamin K in breast milk. But the why is not so important in this instance. Babies, through no fault of their own, are born at increased risk of life threatening bleeding complications from vitamin K deficiency. Vitamin K prophylaxis via the intramuscular route is safe and effective at preventing these life threatening complications, and based on the evidence available it is better than oral regimens. This may change in the future.

When a parent refuses the vitamin K, I can’t force it upon them. I try to get to the bottom of their concerns and address them as best as possible. In the vast majority of instances, parents agree to the injection. When they don’t, we don’t notify child protective services or call the police. We document, document and then document some more so that it is clear in the medical record that the parents were given the appropriate information to make an informed decision and that even knowing the risk they still refused. There is no oral vitamin K solution available in the United States, but I guess you can get anything on the internet these days. Oral dosing is better than nothing. I leave that discussion up to their primary care physician.

Posted by Clay Jones

Clay Jones, M.D. is a pediatrician practicing at Newton-Wellesley Hospital in Newton, MA, and a regular contributor to the Science-Based Medicine blog. He primarily cares for healthy newborns and hospitalized children, and devotes his full time to educating pediatric residents and medical students. Dr. Jones first became aware of and interested in the incursion of pseudoscience into his chosen profession while completing his pediatric residency at Vanderbilt Children’s Hospital a decade ago. He has since focused his efforts on teaching the application of critical thinking and scientific skepticism to the practice of pediatric medicine. Dr. Jones has no conflicts of interest to disclose and no ties to the pharmaceutical industry. He can be found on Twitter as @skepticpedi and is the co-host of The Prism Podcast with fellow SBM contributor Grant Ritchey.