Twenty-eight pregnant patients exhibiting subnormal fetal growth patterns by serial ultrasonic cephalometry were studied. Only 12 (43%) delivered small-for-gestational-age (SGA) infants indicating a poor correlation between the prenatal assessment of intrauterine growth retardation (IUGR) by ultrasonic cephalometry and the neonatal evaluation of the newborn as SGA. The most important factors in the evaluation of the fetus with subnormal serial ultrasonic cephalometry were: 1) the type of ultrasonic growth pattern ("late flattening" vs "low growth profile"), 2) the presence or absence of maternal high-risk factors, and 3) the gestational age of the fetus at the time of detection of the growth abnormality. A pregnancy showing a late flattening type of growth pattern by serial ultrasound in the presence of maternal high-risk factors and with the growth abnormality being detected before 35 weeks of gestation, almost certainly will terminate with the birth of a SGA infant. On the contrary, serial plasma free estriol determinations were not useful in predicting the fetal status at birth. All but 4 of these patients were delivered at term and there was neither perinatal mortality nor significant morbidity. It is suggested that the existence of an abnormal cephalometric pattern is not an indication for early delivery unless fetal distress is detected by means of an oxytocin challenge test.