Key takeaways:
All babies are born with vitamin K deficiency.
Vitamin K shots prevent complications like strokes and other serious internal bleeding.
There’s no evidence that vitamin K shots cause cancer or other long-term health issues.
It may not get as much attention as other vitamins, but vitamin K is essential for health. Our bodies need vitamin K to stop bleeding and make blood clots. Without vitamin K, minor injuries could lead to serious bleeding. And the good news is that getting enough vitamin K is pretty easy. The body is very efficient at holding onto vitamin K from food and making its own stores.
But people with certain medical conditions can develop vitamin K deficiency. These people are at risk of developing disordered bleeding. You might be surprised to hear that there’s an entire segment of the human population that has vitamin K deficiency. That group is newborn babies. If you’re expecting a newborn — here’s everything you need to know about vitamin K deficiency and supplements.
Why do newborns need a boost of vitamin K?
Newborn babies are always born without enough vitamin K. There’s nothing anyone can do to prevent that. Vitamin K comes from food and is made by the bacteria in the small intestine. A newborn isn’t able to store enough vitamin K before they’re born because vitamin K doesn’t cross the placenta very well. A newborn also can’t make their own vitamin K because they don’t have enough gut bacteria for several months.
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Vitamin K is an important player in our body’s ability to stop bleeding. Because newborns don’t have enough vitamin K, they can develop life-threatening bleeding. This bleeding can happen in different places in the body, including:
In the intestines
In the nose
In the brain
Under the skin (as large bruises)
At the umbilical cord
This bleeding is called “hemorrhagic disease of the newborn.” It happens spontaneously, meaning bleeding occurs even without an injury.
Giving vitamin K supplements right after birth helps protect newborns from this serious bleeding for the first 6 months of life. The American Academy of Pediatrics started recommending vitamin K supplements in 1961. Vitamin K supplementation is very effective. Studies have shown that babies who don’t get vitamin K shots at birth are 81 times more likely to develop life-threatening bleeding.
When is vitamin K given to my newborn?
Babies should get a vitamin K supplement as soon as possible after delivery. Birth is traumatic by nature. In order to help stop bleeding that can happen from this trauma, it’s important to give vitamin K within 6 hours of birth.
Waiting to give the vitamin K puts the newborn at even higher risk of bleeding complications. Babies are at the highest risk for hemolytic disease of the newborn right after delivery. But they can still develop bleeding related to vitamin K deficiency throughout the first 6 months of life.
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How is vitamin K given to my newborn?
Providers usually give vitamin K as an intramuscular shot, often in the thigh muscle. The research shows that vitamin K shots can prevent hemorrhagic disease of the newborn. A 1 mg dose is enough to correct the baby’s deficiency and leaves enough left over so that the liver is able to store some. The liver releases the vitamin K over time so that the baby has enough in their system for the first few months of life.
Vitamin K does come in a liquid form. Many parents are interested in oral vitamin K since it isn’t painful like an injection. Several studies looked at whether oral vitamin K can prevent hemorrhagic disease of the newborn. While oral vitamin K can protect against bleeding early on, it isn’t strong enough to stay in the baby’s system. So it doesn't give ongoing protection for the first 6 months of life. Right now, it’s not clear what dose of oral vitamin K will give enough protection or how long babies should take it.
Since the safe oral dose isn’t known, the injection is usually recommended — especially for babies who are only breastfeeding. Vitamin K does transfer very well in breastmilk. It’s not possible to increase the vitamin K levels in breast milk enough to correct vitamin K deficiency by eating more vitamin K or taking a supplement.
Does vitamin K have side effects or cause health problems later?
Side effects to the vitamin K injection are very rare. A scleroderma-like patch at the injection site and anaphylaxis are two possible side effects. But these side effects are rare.
In the 1950s, babies developed anemia and high bilirubin levels after receiving the vitamin K injection. Researchers found this was because of the use of high doses (50 mg) of vitamin K2. Healthcare professionals no longer use that dose or form of vitamin K. Newborns are now given between 0.5 mg and 1.0 mg of vitamin K1, which hasn’t caused hemolytic anemia or high bilirubin levels.
In the 1980s, very premature newborns were becoming sick from benzyl alcohol toxicity. While this ingredient was found in vitamin K, researchers found that there were many sources of benzyl alcohol in other medications that these infants were getting. The amount of benzyl alcohol is much lower in the vitamin K shot today (and in other medications as well). Currently, there aren't any reports of benzyl alcohol toxicity from the vitamin K shot — even in very premature babies.
In the early 1990s there was a study that tried to link vitamin K supplementation to the development of leukemia. Several studies done after this initial study showed no connection between vitamin K and cancer.
The bottom line
Babies have vitamin K deficiency during their first months of life. Vitamin K is a key ingredient in the body’s normal clotting process — without it babies can develop serious internal bleeding. A single vitamin K injection is effective in preventing internal bleeding for a baby’s first 6 months of life. Research shows vitamin K injections are safe and don’t cause long-term health problems. Currently, there’s no evidence to support the use of oral vitamin K, though research is ongoing. In the future, oral supplements may be another option.
Why trust our experts?
References
American Academy of Pediatrics. (2003). Policy statement: Controversies concerning vitamin K and the newborn. Pediatrics.
Centers for Disease Control and Prevention. (2021). Frequently asked questions: Vitamin K and the vitamin K shot given at birth.
Cornelissen, M., et al. (1997). Prevention of vitamin K deficiency bleeding: Efficacy of different multiple oral dose schedules of vitamin K. European Journal of Pediatrics.
HealthyChildren.org. (2019). Where we stand: Administration of vitamin K. American Academy of Pediatrics.
Jullien, S. (2021). Vitamin K prophylaxis in newborns. BMC Pediatrics.
Lippi, G., et al. (2011). Vitamin K in neonates: Facts and myths. Blood Transfusion.
Office of Dietary Supplements. (2021). Vitamin K fact sheet for health professionals. National Institutes of Health.
von Kries, R., et al. (1999). Can 3 oral 2 mg doses of vitamin K effectively prevent late vitamin K deficiency bleeding? European Journal of Pediatrics.
Wariyar, U., et al. (2000). Six years' experience of prophylactic oral vitamin K. Archives of Diseases of Childhood. Fetal and Neonatal Edition.
