Luke Shaw is set to be called up for England's friendly against Denmark.
Hodgson said: "Shaw is the obvious one (to bring in) because he has been playing last season and has been in the team non-stop since the start of this season.
"Before we start really delving in the U18 international team players will have to be really really special if after two games for England Under-18s and suddenly they are in a World Cup squad ahead of the likes of Glen Johnson and Kyle Walker.
"I think that is asking a bit too much. It is may when we make decision."