Trace Elements in Prenatal and Neonatal Development: Zinc and Manganese

A comprehensive review of the role of all trace elements in fetal and neonatal development here is possible at only the most superficial level. Therefore two trace elements, zinc and manganese, are used to exemplify the concepts involved. The points to be made are, first, that maternal dietary trace element deficiencies can affect fetal and neonatal development at several levels of organization. Second, even mild zinc deficiency during pregnancy may have deleterious effects on the offspring; and third, trace element deficiencies that affect the fetus may come about not only through inadequate dietary intake, but through a number of factors that interact with trace elements. When considering the effect of trace elements and their deficiencies on early development, it is important to recognize two principles of developmental nutrition and teratology: time specificity and agent specificity (1). The time during the developmental process at which nutritional insults occur is an important factor in determining the response of the developing organism (2). During critical periods in development, in which organs, tissues, or other components are forming, they are vulnerable to damage, so that even short periods of nutritional deficiencies may have permanent effects. Conversely, the same insult at a later time will not produce the defect. Because of agent specificity, different nutrients with their specific biochemical roles in development may have greater or lesser effects. Thus, different trace element deficiencies may have different final effects on a developing embryo, fetus, or neonate, even though the timing of the deficiency is the same.