The iron endowment at birth depends, in large part, on the newborn's birth weight and gestational age. These are determined by many factors, some of which are maternal characteristics, including the following: maternal iron stores at her own birth and during her own early life, maternal growth and development, maternal age at conception, intergenesic intervals, maternal body characteristics and iron status at conception and during early pregnancy, gestational body weight gain, and iron status throughout gestation, particularly at conception and early pregnancy, and gestational body weight gain. Although less studied, paternal influences on the initiation and progression of pregnancy and on maternal environmental exposures are also important. Even though tools for the quantitative evaluation of women's iron status are very well developed, the quantitative estimation of body iron in the newborn and young infant remains a challenge. This article describes the crucial role played by the placenta in protecting the embryo and the fetus. In addition, neonatal health, particularly early in pregnancy, is briefly addressed, as are some important aspects of antenatal nutritional interventions that include iron.