Nutrition and low birth weight: from research to practice.

Low birth weight (LBW) remains a significant public health problem in many developing countries, and poor nutrition both before and during pregnancy is recognized as an important cause. Emerging evidence on the role of intergenerational effects in determining maternal preconceptual nutritional status indicates the need for continued investment in strategies that improve women's nutrition and health throughout the life cycle, especially during the early years. Controlled trials have shown that improving food intakes during pregnancy effectively reduces LBW, but programs have been less successful because these interventions are expensive and difficult to manage. Multivitamin-mineral supplements have been viewed as a simpler solution, but 2 of 3 controlled trials conducted to date failed to show that multivitamin-mineral supplements are more effective than are iron-folate supplements, which are already the standard of care during pregnancy. Emerging evidence indicating the benefits of iron supplements in improving birth weight illustrate the need for increased efforts to reduce iron deficiency by improving coverage of antenatal programs and promoting fortification. Other causes of LBW include environmental factors, such as smoking; indoor air pollution; and infections, such as malaria. However, little is known about the interactions between nutrition and infection. Underlying social factors, such as poverty and women's status, are also important, especially in South Asia, where more than one-half of the world's LBW infants are born. In summary, strategies that combine nutrition-based interventions, such as improving food intakes and micronutrient status, especially iron status, with approaches that improve women's status and reproductive health are needed to reduce LBW.