OBJETIVE: To evaluate the performance of ultrasound clinical trial proposed by the CLAP. MATERIALS AND METHODS: A descriptive study that evaluates the likelihood of association of small for gestational age (SGA) with factore risk and ultrasound findings. RESULTS: Correlation between risk factors and the cranial circumference (CC) and abdominal (CA) lower 5th percentile dle with PEG was found. CONCLUSIONS: A significant association between risk factors and the presence of small for gestational age fetus. The high specificity and negative predictive value DC and AC make this biometrics useful for the assessment of fetal growth.