Vitamin K is important to blood clotting. Newborn babies can have low levels of Vitamin K from birth to 6 months of age due to low levels received through the placenta. They are produced by the liver or in breast milk The injection greatly reduces the risk of vitamin K deficiency bleeding. This is called hemorrhagic disease of the newborn. Vitamin K deficiency bleeding can be potentially fatal. It can lead to internal bleeding, especially in the brain. Early symptoms include easy bruising, blood in the stool or urine, or oozing from the umbilical cord. Most babies get an injection of vitamin K in the upper thigh. This may be briefly painful to the baby, but it doesn't seem to cause babies any pain afterward. Oral Vitamin K does not provide enough protection against this condition and is not recommended. Without the vitamin K injection, babies are about 80 times more likely to have vitamin K deficiency bleeding. This bleeding can lead to death or serious long-term disability.
If you have concerns about either of these treatments, talk with your baby's doctor.