Fetal malnutrition was diagnosed in white, full-term infants who had low ratios of birth weight to body length in the presence of characteristic physical signs of malnutrition and in the absence of clinical evidence of congenital defects and intrauterine infections. The maternal factors significantly associated with fetal malnutrition included a poor maternal weight gain, lack of prenatal visits, the unmarried state, preeclampsia, chronic major illness, and obesity. Two or more of these six maternal factors occurred in 51% of pregnancies involving malnourished infants, and in 9% of pregnancies involving control infants.