6.2 Data monitoring Editorial Board of Chinese Journal of Evidence-Based Pediatrics will be in charge of data monitoring of the clinical trial. CJEBP will provide data monitoring of the clinical trial to FrieslandCampina regularly in at middle experiment stage and later experiment stage. During the trial, CJEBP will investigate 6 research centers for their quality of practice at least one time, without any announcement in advance. The monitoring subjects include child care doctors, nurses and guardians of subjects enrolled in this trial.