I have a stairway leading to my basement. I am going to put up a gate
across the stairs. There is an existing guard around the rest of the
stairway. As I see it the code for this guard is asking for a maximum
spacing of 4 inches. The existing guard meets this specification. In
looking at code for gates it appears that the minimum spacing is 2 3/8
inches. Why closer spacing for gates as opposed to guards? Anyone
ever see a baby with a 2 3/8 inch head?

The purpose of the gate is to keep adults from falling down the
stairs, no babies involved.