Prevention of low birth weight and pre-term birth: literature review and suggestions for research policy.

Mortality during the first week of life has greatly decreased in developed countries, but the gains have been unevenly distributed across socioeconomic groups and geographic areas. Among many explanations for these differences, low birth weight is shown to be significant in the United States, Sweden, and Finland. An imbalance between potential benefits to be gained and the paucity of experiments reporting on this is noted.