From the same people who brought you the anti-vaccine movement comes a new, ill-founded parental trend—refusing a shot of vitamin K, which prevents brain bleeds in newborns.

True fact: as a general rule, medical interventions were created to prevent or treat illnesses or injuries.

I mention this because there appears to be an increasing strain of suspicious thinking about why medical providers do the things we do. Concerns either about some ill-defined malign intent or hamfisted incompetence drive some people to refuse interventions with well-established benefits, sometimes with the potential for catastrophic harm.

To wit, a distressing trend by some parents to refuse vitamin K injections for their newborns. This is an absolutely terrible idea.

Vitamin K is found in many foods, including green leafy vegetables, and is also produced naturally by bacteria in our gut. However, newborn babies don't yet have a population of these bacteria at birth. The vitamin also does not cross the placenta well, and so they are born in a state of relative deficiency. Furthermore, breastmilk is low in the vitamin, no matter what the mother eats. (As one doctor put it, "All the kale in the world won't do it.")

The reason correcting this deficiency is important is that vitamin K is necessary for the blood to clot properly. Newborns who remain deficient are at risk of internal bleeding. In 2013, four newborns whose parents declined the vitamin shot in Tennessee were admitted to the hospital, three of which for hemorrhages in the brain and one with gastrointestinal bleeding. At the time those cases were reported, it was unclear what kind of developmental damage the brain bleeds had caused. What is clear is that the damage was preventable.

Yet despite the manifest benefit of protecting infants from hemorrhaging, you can still find people on the Internet telling parents not to let their children get the vitamin K shot. This list includes Dr. Oz's chum Joseph Mercola, who cites concerns about psychological trauma, high dosage, and possible infection as reasons not to get the shot.

I assure you that the trauma from a brain bleed is substantially greater than that from a brief one-time injection, and that the dose is correctly calculated to deliver the appropriate benefit. We prevent infection with a complicated process known as "cleaning the skin first," which has proven to be highly effective.

Parents-to-be, I cannot implore you sincerely enough—do not listen to these people.