The vitamin D defficiency and insufficiency rate regarding age group Age group (month) Studied number (n) Defficient vitamin D number (n) Percentage (%) p 0-< 12 13 10 76.9 0.233 12-<24 92 54 58.7 24-<36 107 54 50.5 36-<48 111 69 62.2 48-<60 83 51 61.4 Tổng số 406 238 58.6 Remark.