Male Pediatrics medicine.medical_specialty Adolescent Cross-sectional study education MEDLINE Comorbidity Northern finland D DEFICIENCY 03 medical and health sciences 0302 clinical medicine 3123 Gynaecology and paediatrics Neoplasms 030225 pediatrics Prevalence medicine Vitamin D and neurology Humans Prospective Studies Vitamin D Child Prospective cohort study Finland business.industry Infant Vitamin D Deficiency medicine.disease Hematologic Diseases Cross-Sectional Studies Child, Preschool Pediatrics, Perinatology and Child Health Female business 030217 neurology & neurosurgery