Objectives to study the correlation of leptin between maternal serum and cord blood and to know relationship between leptin and fetal growth, and the origin of leptin.

Objective To study the content of Zn, Cu, Fe, Se in maternal blood, hair, cord blood, amniotic fluid and the relationship between each sample, the trace elements and the growth of their infants.

Objective To explore the relationship between leptin's quantity in maternal blood, amniotic fluid, umbilical blood and maternal and newborn's weights.