It is widely accepted that micronutrients have a major function in many periods of women's life, particularly during pregnancy and lactation. Inadequate stores or intake of micronutrients might have adverse effects both to the mother (hypertension, anemia, complications of labor) and the fetus (congenital malformations, pre-term delivery, intrauterine growth retardation). The effect of improper nutrition is influenced by gestational age, severity of deficiency, or both. Generally, the daily requirements in minerals and trace elements are easily met in women having a balanced diet. Such diet during pregnancy should provide the recommended daily allowance of all nutrients except elemental iron. Consequently, deficiency states are supposed to be rare in developed countries, and supplementation should be made on an individual basis. On the other hand, nutritional deficiencies during pregnancy might be difficult to detect. Studies from developing countries where micronutrient malnutrition is common during pregnancy gave us strong evidence that supplementation of certain trace elements and minerals could prevent some of the most severe adverse pregnancy outcomes. While some micronutrients have been studied extensively (e.g. calcium, iron, zinc, iodine), much less is known about others. It has been shown that multiple micronutrient deficiencies, rather than single deficiencies, are common. Our knowledge about the significance of interactions between micronutrients in relation to pregnancy outcome is limited. The role of these interactions in improving pregnancy outcome need to be investigated more precisely. According to the summarized data, the potential benefits of routine supplementation seem to outweigh any potential adverse reaction that can be attributed to their consumption.