This retrospective study included a review of medical reports of 1035 patients (aged 1-3 years) who presented to our hospital between October 2011 and October 2013. The children were divided into 3 groups: Group 1: those supplemented with vitamin D₃ (400 IU/day), Group 2: those supplemented with multivitamins, which included 200-400 IU/day of vitamin D₂ or D₃, and Group ₃, the controls: those not supplemented with vitamin D