It common to give a vitamin K shot to babies shortly after birth. It is usually done in order to decrease the chances of bleeding into the brain shortly after birth.
One article (1) looked at vitamin K and the risk of giving it to babies who receive the vitamin K shot. They found that research has indicated that the vitamin K shot might cause cancer in babies who receive the shot. The babies receive twenty thousand times more vitamin K than they really need.
The article noted that this overdosing of babies on vitamin K may be linked to getting cancer later in life. It also noted that parents should think twice about agreeing to give vitamin K to their newborns as it might do them more harm than good.
Source: 1.The dark side of the Routine Newborn Vitamin K shot. http://articles.mercola.com/sites/articles/archive/2010/03/27/high-risks-to-your-baby-from-vitamin-k-shot-they-dont-warn-you-about.aspx. Accessed 9/13/16.