Vitamin K is a nutrient that helps blood clot or stop bleeding. Most adults get vitamin K from their food. Bacteria in the large intestines also make some vitamin K that the body can absorb.

Healthcare professionals recommend all babies receive a vitamin K injection at birth to help their blood clot effectively. New parents often have questions about these preventive measures for newborns, which also may include screenings for genetic conditions and antibiotic eye ointment to prevent eye infections.

Here are answers to common questions new parents ask regarding vitamin K:

How is vitamin K administered to infants?

Since 1961, the American Academy of Pediatrics has recommended a single dose of vitamin K injected into the thigh muscle of a newborn infant to prevent bleeding. The recommended dose is based on the infant's weight and given within six hours of birth.

Why does my baby need vitamin K at birth?

A newborn typically has a low level of vitamin K in their blood at birth. Even if the pregnant person has a diet sufficient for vitamin K, only a minimal amount is transferred across the placenta before birth and is not enough to protect the baby after birth.

Although breast milk is the best nutrition for all infants, it has a relatively low level of vitamin K. While formula has more vitamin K per fluid ounce than breast milk, a baby is still at risk for a vitamin K deficiency without an injection after birth.

According to the American Academy of Pediatrics, recent evidence also shows that a postpartum person taking high doses of vitamin K while breastfeeding doesn't increase the level passed to the baby enough to prevent the risk of vitamin K-deficient bleeding.

Is vitamin K safe for infants?

There is no evidence that vitamin K injection causes any harm to the baby. Parents can minimize the short-term discomfort from the injection by holding or feeding the infant while it's administered.

Vitamin K is not a vaccine, doesn't contain mercury and has been proven to be safe and beneficial for over 60 years.

How quickly after birth does vitamin K deficiency develop?

Vitamin K deficiency occurs in male and female infants and can develop during these time frames after birth:

• Early onset — occurs on the first day of life
• Classic onset — occurs between day two and the first week of life
• Late onset — occurs between eight days and six months

What is vitamin K-deficient bleeding?

Vitamin K-deficient bleeding can happen when a baby does not have enough vitamin K. Healthcare professionals have known about the condition, also known as hemorrhagic disease of the newborn, for many decades. New parents may be unaware of vitamin K-deficient bleeding because it's become less common now that most infants receive the injection.

There is a risk of bleeding in the body up to 6 months of age in infants who don't receive a vitamin K injection at birth. These babies are 80 times more likely to experience severe bleeding.

What are the signs or symptoms of vitamin K-deficient bleeding in babies?

Infants who don't receive a vitamin K injection at birth may have no warning signs of bleeding for days, weeks or months. Symptoms include bruising easily, paler than usual skin or blood in the stool. Vitamin K-deficient bleeding can occur in various parts of the infant's body, such as the skin, umbilical cord, nose, mouth, gastrointestinal tract and brain. Bleeding in the brain can be life-threatening and cause brain damage or death.

Can my baby receive vitamin K orally instead of as an injection?

Oral vitamin K supplementation isn't recommended because it's less effective and requires multiple doses over several months to achieve the same benefit as the one-time shot. The Food and Drug Administration (FDA) has not approved an oral vitamin K for newborns.

Why is vitamin K essential for male newborns?

Before the recommendation of vitamin K injection at birth in the U.S., infant males had an increased risk of bleeding during circumcision. At that time, one out of every nine baby boys who had an elective newborn male circumcision without vitamin K had bleeding that wouldn't stop.

The risk of bleeding during circumcision has significantly decreased since vitamin K supplementation became the standard of care in the U.S. For parents who choose an elective newborn circumcision, administration of vitamin K is required before the procedure.

Having your newborn receive vitamin K at birth reduces the risk of severe bleeding. Talk with your baby's healthcare team if you have questions about vitamin K.

Dennis Costakos, M.D., is a neonatologist in La Crosse, Wisconsin.

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The American Academy of Pediatrics policy statement is dated Feb. 22, 2022. Dr. Costakos is the first author of one of the cited references for the best dosing of vitamin K for premature babies.

This article first appeared on the Mayo Clinic Health System blog.

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