I work on a peds med/surg floor and on all new admissions, the doctors have to draw labs & start IVs... after that, it falls on nursing. However, we are lucky enough to have doctors that are willing to help you out. If I know I am not going to get an IV on a dehydrated chubby 10mo & its 3am, the kid is screaming, the parents are upset, I will page the doctor to see if they can try. Otherwise, we as nurses have to try once before we call the docs. I haven't been a nurse that long & I get extremely nervous when it comes time to start an IV on anyone less than 5yo but I just bite the bullet & go for it... more times that not I have been successful. Its just a matter of getting experience.