A randomized controlled trial of prenatal nutritional supplementation in New York City.

This randomized controlled trial of nutritional supplementation in pregnancy, in a poor black urban population in the United States, aimed to increase the birth weight and influence the postnatal development of the offspring of mothers at high risk of having low birth weight infants. The execution of the research design and adherence to the treatment regimen among the experimental population appeared adequate for a reasonable test of the treatments. At birth, the only significant favorable effect of supplementation observed was the prevention of depressed birth weight among the offspring of mothers who smoked heavily. With balanced protein-calorie supplementation, length of gestation was increased, the proportion of low-birth-weight infants reduced, and mean birth weight raised by 41 gm (not statistically significant). With high protein supplementation, there was an excess of very early premature births and associated neonatal deaths, and there was significant growth retardation up to 37 weeks of gestation. At 1 year of age, significant effects of high protein supplement were found on three psychological measures: visual habituation, visual dishabituation, and mean length of free play episodes. These measures were unrelated to measures of growth at birth and at 1 year of age. There were no detectable residual adverse effects of high protein supplementation at 1 year of age.