Evidence that maternal undernutrition contributes to the problem of low birth weight in industrial societies will be discussed in the following categories: (1) epidemiological associations, (2) clinical studies of growth-retarded babies, (3) maternal dietary studies, and (4) pathologic findings in perinatal deaths.
Mean Birth Weight.—As summarized by Rosa and Turshen,1 quite large differences between populations occur with respect to mean birth weight. In contrast, differences in mean length of gestation are minor. Thus, between-population variance in mean birth weight reflects principally differences in rate of fetal growth. It is a central problem of perinatal medicine to know the relative contributions of heredity and environment to the variance in fetal growth rate, and, among the environmental factors, to know the effect of maternal undernutrition.Within industrial societies, similar though less obvious differences are seen in the mean birth weight. For example, mean weight at term for male