4.4 Recruitment and Statistical Analysis 4.4.1 Recruitment: Infants will be equally allocated to the 4 dosage groups, based on a randomization in blocks of 8 to accommodate stratifying by gender since growth diverges in male and female infants by the first year of life. Even distribution among the 4 seasons (standard calendar dates) will be sought by recruiting 1/12th of the sample each month. The fact that some infants may have already began vitamin D supplements will be considered as a systematic error.