I still have a bit of time before I apply, but I was wondering it would be an negative aspect if most of my activities were concentrated in one area. All of my clinical and nonclinical volunteering is in pediatrics and child focused (NICU, PICU, Tutor for at risk youth) Should I volunteer in another area or am I good with my interests in pediatrics?
You would broaden the appeal of your application with exposure to other age groups. After all, for most of your clinical years you'd be required to have interactions with adult patients. I agree it would be fine to do this through shadowing experience.
Going to echo the other sentiments here- you're only going to spend 6-8 weeks with kids in your first three years of medical school, so showing interest in other areas might make you more broadly appealing to adcoms by showing the remainder won't be misery for you.