Why are newborn vitamin K shots necessary?

Sometimes it's a relief to "lose" a patient to another physician. My colleague was on call and about to examine a newborn when the hospital staff informed him that the parents had declined the standard newborn vitamin K shot and were planning to administer their own supply of oral vitamin drops to the baby.

The doctor, an advocate of science-based medical care, hoped to convince the parents to reconsider when he was told that the family had, in fact, already selected another physician to see their newborn.

It was in some ways a relief since pediatricians know that it's bound to be a difficult 18-year relationship if new parents already distrust carefully researched medical science and turn instead to fringe bloggers as their go-to health care guides.

Just what is the deal with these standard newborn vitamin K shots? Apparently some websites fan the flame of parental fear by claiming that vitamin K injections cause childhood cancer. This, however, is not the case and there exists no credible, reproducible evidence to support such a claim.

The proven and most important feature of vitamin K shots is that they are potential lifesavers. Since 1961, the American Academy of Pediatrics has recommended that every newborn receive an intramuscular injection of vitamin K at birth to prevent hemorrhagic disease of the newborn, now referred to as vitamin K-deficient bleeding (VKDB).

In their article in Pediatrics in Review, Drs. Johanna Warren and Carrie Phillipi explain that newborns have low levels of vitamin K since they lack the gut bacteria to make this vital clotting factor. Vitamin K also does not pass well across the placenta, the fetal liver is unable to store the vitamin, and breast milk is a "poor source" of vitamin K.

The Review authors note that VKDB can result in neonatal skin bruising, bleeding of mucous membranes, bleeding at the umbilical cord and circumcision site, as well as fatal intracranial hemorrhage.

The AAP confirms that both injectable and oral vitamin K can prevent the early vitamin K-deficient bleeding seen in the first two weeks of life. At the same time, AAP experts caution that vitamin K shots are still the most effective preventive treatment available against the late-onset VKDB which occurs in infants between 2 weeks and 12 weeks of life.

Warren and Phillipi conclude, "There is not enough information about the efficacy of oral vitamin K to recommend its routine use, although it is certainly better to use oral vitamin K than none at all when parents refuse the intramuscular formulation."

Though not as commonly seen as during the pre-prophylaxis era, neonatal vitamin K-deficient bleeding still occurs. In 2013, the Centers for Disease Control and Prevention reported four cases of late VKDB in Tennessee.

All four infants did well at birth but developed intracranial hemorrhage or gastrointestinal bleeding between 6 weeks and 15 weeks of life. The parents of these newborns had declined vitamin K prophylaxis for one of three reasons: fear of leukemia, a wish to avoid exposure to "toxins," or a feeling that the vitamin K shot was "unnecessary."

• Dr. Helen Minciotti is a mother of five and a pediatrician with a practice in Schaumburg. She formerly chaired the Department of Pediatrics at Northwest Community Hospital in Arlington Heights