I use it on small children as well as older because it is so dangerous for them to have the insect bites. I just always spray where they don't get it into their face mouth and hands or anything that would go into their mouths. Like moms shoulders when being held. Or moms hands spraying clothing is a good thing and will keep them away just as well as on their skin. Got to stay protected and it is much nice with a product that is not greasy and messy.
I wouldn't spray anything near a child that young. BUT You could try and spray the back of their pant leg or part of their stroller. Obviously without them in the pants or Stroller. I would always ask a pediatrician their opinion.