If you’re giving birth in a hospital, your medical provider may have told you to expect frequent visits and interruptions from doctors, nurses, lactation consultants, and other staff. Doctors will assess your baby from head to toe to make sure they look perfect and healthy. The nurse will take measurements for height, weight, and vital signs. For some tests and procedures, they may take your newborn to the nursery for a short time, and for others, your baby can stay in your room.11,12,13 One of these standard procedures is the vitamin K shot at birth.
Vitamin K is a fat-soluble vitamin, meaning it’s stored in the body’s fat and liver. It stays in the body longer than water-soluble vitamins, which are easily excreted through urine. However, vitamin K breaks down relatively quickly inside the body and can be expelled through urine and feces, which prevents overdose or vitamin K toxicity. The American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) recommend all newborns get the shot, which is most effective when administered within six hours after birth.1,2,3
What Does Vitamin K Do?
Vitamin K helps make up several proteins that aid blood clotting, such as prothrombin. Blood clotting helps prevent excessive bleeding or hemorrhage. Vitamin K is also a significant component of osteocalcin, a protein that helps build healthy bones.2
What Is the Vitamin K Shot?
The vitamin K shot is a one-time dose administered intramuscularly into a newborn’s thigh. In a full-term infant, the standard amount is 1 milligram. Preterm or particularly small newborns may receive a smaller dose based on the baby’s weight and gestational age.3
The vitamin K shot at birth isn’t a vaccine. Although it’s an injection administered into a muscle, similar to many vaccines, it doesn’t trigger the baby’s immune system.4 Ingredients in the shot are:1,5
- Vitamin K: This is also called phytonadione.
- Polyoxyethylated fatty acid derivative: This is an emulsifier that keeps vitamin K evenly mixed as a liquid. This ingredient can cause a rare allergic reaction in adults but not babies since they aren’t sensitized to allergens yet.
- Hydrochloride: This balances the pH of the solution so it isn’t too acidic or too alkaline. This can prevent it from burning or stinging upon injection.
- Dextrose: This is a simple sugar.
- Benzyl alcohol: There’s a small amount of preservative to prevent bacterial growth. Benzyl alcohol is a common, safe ingredient in many medications. You’d have to give a newborn one hundred times this dose on a daily basis to start seeing any side effects. Babies only require one shot to prevent severe bleeding.
How Does the Shot Work?
An infant’s bloodstream immediately absorbs the vitamin K upon administering the shot, providing them a quick initial dose of this essential nutrient to prevent bleeding in the first few days of life. The liver stores the rest of the vitamin for the next two to three months. It’s slowly released over time until the infant’s diet takes over supplying the essential vitamin K.1
Side Effects and Risks
The vitamin K shot at birth is safe, but minor risks include:1
- Injection site reaction with pain, bruising, or swelling
- Scarring of the skin at the injection site
- Allergic reaction to one of the other ingredients in the shot, which is extremely rare (there’s only been one reported allergic reaction to the vitamin K shot)
One British study in the 1990s linked the vitamin K shot to an increased risk of leukemia. However, this was refuted. Multiple repeat studies found that the vitamin K shot was NOT a cause of leukemia.6
Is the Shot Mandatory?
No, although it’s standard and highly encouraged for every newborn. The AAP has recommended it for newborns since 1961.7 Unless you explicitly refuse the shot, it’s routinely given if you give birth in the hospital, in a birth center, or at home. If you decide to opt out of the shot for your baby, you’ll need to sign a form stating that you understand the risks of forgoing this life-saving, preventative intervention.8
What Is Vitamin K Deficiency in a Newborn?
Nearly all newborns are born with low levels of vitamin K because it doesn’t readily cross the placenta while the baby is in the womb. This means increasing the mother’s dietary or supplemental intake of vitamin K during pregnancy won’t raise the baby’s vitamin K levels. Newborns’ intestines also haven’t been colonized with good bacteria yet, so there’s no way for them to make vitamin K for a while.7
Since vitamin K is essential to blood clotting, low vitamin K levels can contribute to vitamin K deficiency bleeding (VKDB) in infants. This condition occurs when babies up to 6 months old experience significant bleeding, either inside or outside their bodies. If the bleeding occurs inside an infant’s body, it often bleeds into the brain or gut, going unnoticed until causing severe symptoms. Internal bleeding can cause death in 20% of cases; that means 1 in 5 babies who develop VKDB will die. In cases where the infant survives, adverse effects of the bleeding may persist. For example, a brain bleed can cause severe, long-term neurological damage, including developmental and motor issues.9
Sources of Vitamin K
Because a newborn’s diet consists only of breast milk or formula, they don’t consume the variety of foods that provide them with this nutrient. Breastfed babies may be particularly deficient in vitamin K because breastmilk contains minimal vitamin K.8,10
Children and adults can consume vitamin K through diet. We get vitamin K through green, leafy vegetables, fermented foods, and animal products like meat, dairy, and eggs. Good bacteria also produce vitamin K in the gut.1,2
Alternatives to the Shot
While maternal diet and nutrition during pregnancy and breastfeeding are essential, maternal supplementation of vitamin K isn’t typically sufficient to increase a baby’s vitamin K levels through breast milk. This is because vitamin K doesn’t cross readily into breast milk, even at high maternal doses, and babies’ guts are inefficient at absorbing vitamin K.1,9
In parts of Europe and Canada, parents can opt for oral administration of vitamin K instead of the shot. This requires multiple doses at different points in the infant’s first months of life. There’s no licensed oral infant dose of vitamin K in the United States, though some people elect to administer the shot’s contents orally. Still, this isn’t recommended or approved.5
The CDC doesn’t recommend an oral dose of vitamin K as an alternative to the shot because newborns don’t consistently absorb vitamin K through the stomach and intestines.10 Since the oral route of administration requires multiple doses, compliance for completing the series is also difficult to achieve. So, these babies are overall more likely to have VKDB and severe complications from bleeding.6
The Bottom Line
Unfortunately, the vitamin K shot for newborns has become controversial in certain circles due to misinformation. Rest assured that the vitamin K shot is an extremely safe procedure to easily prevent severe brain bleeds and other bleeding problems in young infants.
You can easily feel overwhelmed by decisions surrounding the birth of your newborn baby, including whether to get the vitamin K shot at birth. You may hear tons of information about interventions before or after delivery from friends, family, and health care professionals. Researching these decisions from trusted sources can prevent you from feeling overwhelmed and help you confidently decide what’s best for your baby.
