Why Newborns Need Vitamin K

Newborn being examined in hospital.

The past decade has seen a decline in newborns receiving the vitamin K shot at birth. More parents have been declining this vitamin supplement for their newborns, which can have devastating consequences. I hope to dispel some of the misinformation out there and explain why it is needed.

The vitamin K shot is not a vaccine. 

It is a vitamin supplement given by injection into the thigh muscle. This has been used since 1961 and is the standard of care set by the American Academy of Pediatrics after recognizing its life-saving benefit.

Babies are born with only a very small amount of this vitamin, not enough to do its job. They are unable to make it due to an immature gut, liver, and microbiome. Vitamin K crosses the placenta poorly, so even though a mother might increase her intake, very little will pass to her infant who will be born with deficient amounts. 

What is Vitamin K?

Vitamin K is a micronutrient - something required in small amounts for our health. It is essential for producing the proteins needed for blood clotting and for maintaining strong, healthy bones. It also contributes to heart health.

Without it, the body is unable to stop bleeding by clotting the blood. Newborns are born deficient in this vitamin. If not supplemented (by the vitamin K shot), they will remain deficient for 6 months.

How do we get vitamin K?

Vitamin K comes from food and is also made in our gut by the microbiome. Since babies don’t eat solids for the first 4-6 months, have an immature gut, and don't yet have a developed microbiome, they remain deficient.

Oral vitamin K is not absorbed well by an infant’s gut. There is not enough in formula or breast milk, even if a mother supplements her diet.

Some vitamin K-rich foods including green leafy vegetables, berries, and nuts.

Foods containing vitamin K include green leafy vegetables, chicken, soybeans, egg yolks, some berries and nuts, and fermented foods. Babies won't eat these vitamin K-rich foods until closer to 6 months.

Why do we need this vitamin?

Vitamin K is used to make clotting factors, and without it, the body is unable to stop bleeding. Bleeding can occur without warning inside the body (such as in the brain or intestines) or outside the body (from the umbilical cord or a circumcision).

Vitamin K is a fat-soluble vitamin, meaning it is stored in the liver. This is why only one dose is required and lasts up to 6 months. Why so long?

Because the primary source of nutrition for the first 6 months is breast milk or formula, both of which have inadequate amounts. Vitamin K from these sources is not well absorbed by an infant’s gut. Oral vitamin K (by mouth) is not absorbed adequately to overcome the deficiency. 

What does vitamin K do for babies?

Vitamin K is required to make clotting factors to prevent bleeding in the body. Without this vital nutrient, the body cannot clot blood to prevent bleeding. If you don’t have enough vitamin K, spontaneous bleeding can occur without any injury. The most dangerous bleeding can occur internally, in the gut or brain, which can lead to devastating consequences, even death.

A newborn who does not receive this shot is 81 times more likely to have spontaneous bleeding, which can carry a 20% risk of death.

Vitamin K-deficient bleeding comes in three forms:

• Early-onset, within 24 hours of birth. This can be seen as bruising, or bleeding from the nose or umbilical cord or circumcision. Note, if an infant does not receive vitamin K, they should not have a circumcision. Your doctor may refuse this procedure since it could cause life-threatening bleeding.

• Classical, 2 days to 1 week after birth. This will cause prolonged bleeding from the umbilicus, bruising, and blood in the stools or vomit

• Late-onset, 1 week and up to 6 months after birth. This is the most dangerous form since many of these infants will develop bleeding in the brain. Unfortunately, by the time this is recognized, it is often too late to treat and carries a 20% risk of death…1 in 5 will die. 

Even if treated, permanent brain damage can occur. Bleeds are usually spontaneous, without injury or warning.

These are all completely and easily prevented.

The dose of vitamin K given to newborns is higher than the daily recommended amount. This ensures that some vitamin K is rapidly available in the bloodstream to provide immediate protection, while the rest is stored in the body and released gradually over several months. This sustained supply keeps babies protected until they can obtain enough vitamin K from their diet.

What are the side effects of the vaccine?

Typically, there can be pain, redness, or mild swelling at the injection site, but this is infrequent. There is no mercury in the shot. There is a benzoyl alcohol-free form (benzoyl alcohol is used as a preservative) that most hospitals stock for use in newborns. You can check for this.

I encourage every parent not to rely on social media for information on this life-saving measure. Have the conversation with your doctor and understand the reasons for it and the risks of going without. Your child deserves that. Parents and doctors both want to do what is in the best interest of your baby.

If this information sounds harsh, that’s the reality. I am in the business of keeping kids healthy lifelong. Having an infant die from an easily preventable condition is absolutely tragic.