Vitamin D Status and Impact on Bone Mineralization in Human Milk Fed Hispanic and Caucasian Infants

In recent years, severe vitamin D deficiency has resurfaced as a major public health concern. Nutritional rickets is widespread, and a recent report on this disease in Texas showed Hispanic children are at increased risk. Long-term follow-up has demonstrated that vitamin D deficient infants are more likely to have decreased bone mineral status in late childhood. Additionally, vitamin D deficiency has been linked to changes in fetal "imprinting" and increased susceptibility to autoimmune diseases, immune deficiency, and malignancy. At birth, an infant's vitamin D status is entirely dependent on the vitamin D status of the mother. Many studies have shown vitamin D deficiency is very common in mother-child pairs, especially in dark-skinned individuals. However, few data exist regarding the vitamin D status in Hispanic infants. Low milk intakes and decreased sun exposure with urbanization makes this a very high-risk group among infants in Texas.

Potential subjects will be identified by study personnel in labor and delivery at St. Luke's and Ben Taub Hospitals and in the normal newborn nurseries. The parent/guardian will be approached and the study will be explained in full. A time for questions will be allowed. Once the parent/guardian agrees to his/her child's participation, an informed written consent form will be signed. Subject confidentiality will be maintained within limits of the law. All names and personal information will be accessed only by the investigators and authorized personnel. There will be no possibility of coercion as subjects will not have any relationship of dependency with the investigators.

A cohort of Hispanic and Caucasian infants will be recruited and followed. Other ethnic groups will not be excluded, but will not be analyzed in terms of the primary outcome. Race and ethnicity will be classified according to mother's self classification. The interventions will not differ between the groups.

This study includes 3 study visits:

1. Baseline inpatient visit at birth - while hospitalized to obtain consent, obtain cord blood sample, and mother to complete a questionnaire
2. 1 week after initial hospital discharge - first outpatient visit to obtain other baseline data (see below) and to start the vitamin D drops
3. At 3 mo of life - second outpatient visit to obtain final data (see below) and discontinue vitamin D drops