Vitamin K is a key substance our bodies need to clot blood.

For adults, vitamin K deficiency is not a major concern because gut bacteria help to ensure our bodies have enough. But newborn babies, with little of their own vitamin K and no gut bacteria, need a shot of the stuff.

With some parents shunning vaccines out of fear, opposition to newborns’ vitamin K shots seems to be rising, too. Experts say some parents are refusing the shots for their babies, a decision that can have deadly consequences.

There is little data on how many parents are taking this route. So a group of researchers from the Centers for Disease Control and Prevention decided to look at the issue in their local community after seeing several babies develop what’s known as “vitamin K deficient bleeding.”

They reviewed birth records for several Nashville facilities over a 10-month period. While not many hospital births involved a vitamin K refusal, private birthing centers were different. After analyzing data on babies born at four such centers in Tennessee, the researchers found that in 28 percent of births, parents refused the vitamin K shot for their newborns.

Missing this shot can be devastating for babies. Bleeding in the digestive tract, external bleeding, brain bleeding and anemia are some of the serious problems caused by vitamin K deficiency.

Increased fussiness, seizures and bruising or bleeding that can’t be explained are key signs that an infant may not have enough vitamin K.

Parents-to-be who remain concerned about the shot should consult a pediatrician to get clear guidance before the birth. The bottom line remains the same: vitamin K shots are a safe and necessary part of welcoming baby into the world.