Hi, that will depend on which type of Vit K he was given.
K1 affects blood clotting, and is often the only type of Vit K that your doc has heard of.
K2 is the one that works with D3, magnesium and calcium, that grows strong bones and teeth and makes sure that the circulating calcium in the blood goes to where it is needed - and not to form atherosclerosis. Not that your baby will be formin atherosclerosis for several decades. If ever.
Dietary sources for K2 are pretty sparse in the western diet. Although good quality stinky cheese is a good source. In the Eastern diet natto is popular, and more K2 is eaten as a result. I would rather chew my own arm off than eat natto. So I supplement.