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Is it really necessary for newborns to get the vitamin K shot? I’m going to have my first baby soon, so I’ve been reading up on vaccines and other things to expect, and it seems like there’s some debate around the shot. Why is that?
— Anonymous
For decades, it has been standard to give newborns a vitamin K shot at birth. The aim is to
prevent a potentially fatal bleeding disorder.
In recent years, however, more parents have been declining this treatment, possibly as a result of a broader distrust of the medical system and possibly because of a false belief that this shot is a vaccine. Between 2017 and 2024, the share of parents refusing this shot increased from 3% to over 5%.
I understand, especially given the increasing noise around vaccines, why parents might be hesitant. However, getting this shot is very important, safe, and can be lifesaving.
The reason for the vitamin K shot is that vitamin K deficiency in a newborn or small infant is a risk for excessive bleeding. Sometimes this is external (as in the case of a cut), and other times it can be internal and spontaneous, including in the brain, which can be deadly. This complication is most common in the first week of life (2 to 7 days), but it can also happen several weeks later. Vitamin K is required by your body to activate clotting factors, which is why a deficiency can cause serious problems. Infants are more likely to be deficient as they don’t produce the vitamin as easily on their own.
Incidence rates of vitamin K deficiency-related bleeding vary, although it is rare in developed countries — estimates from Europe put the prevalence at 4 to 7 in 10,000. Even with this very low prevalence, among 4 million births in the U.S. in a given year, we would expect about 1,600 cases without prevention.
A vitamin K injection at birth has been shown to be very effective at largely eliminating this bleeding risk. It is important to note that although vitamin K is typically delivered in a shot, it is not a vaccine; it is a vitamin. It doesn’t prompt the immune system to do anything the way a vaccine would. Vitamin K can also be delivered orally, though this requires more dosing (not generally the preferred route, although it may be an option in some cases).
One issue that people sometimes raise when discussing the vitamin K shot is a concern that it might increase the risk of childhood cancer, in particular, leukemia. A small case-control study from 1992 is the source of this claim, but subsequent, better data did not support this.
The bottom line is there is no reason to think these shots increase the risk of cancer or have other significant risks. And they are potentially lifesaving, so ultimately a very good idea to do.
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