A prospective study on 25 adolescent pregnant women was carried out. A single measurement of the systolic-diastolic ratio (S/D) was taken using continuous Doppler on arcuate arteries on both sides of the uterus. All measurements were taken after the 16th week of amenorrhea. The relationship between Doppler velocimetry and birthweight was established. Seven newborns were small for gestational age. The sensitivity of this method was 94.4% and specificity was 57.1%. Positive predictive value was 80.0% while negative predictive value was 85.0%. The importance of measuring both arcuate arteries and determining the site of placental insertion for proper interpretation of results is stressed.