ABSTRACT: The main conclusion of this review of 8 nutritional intervention studies during pregnancy is that, in mothers with protein-energy malnutrition–either acute or chronic-food supplementation during pregnancy can improve birthweight and decrease the incidence of low birthweight babies. It is stressed that programs to reduce the incidence of low birthweight babies must be aimed at the major causes of low birthweight, which differ among populations. For example, in Harlem the major probable cause of low birthweight is not dietary protein-energy deficiency but short birth intervals, very young primiparas, highparity, and smoking.