Ultrasound assessment of fetal biparietal diameter and femur length during normal pregnancy in Iranian women.

OBJECTIVES To determine the pattern of intrauterine growth and predicted biparietal diameter (BPD) and femur length (FL) at point in gestation of Iranian fetuses. METHODS In an extensive and long-standing prospective study in Tehran, Iran 15693 BPD and 15594 FL measurements were obtained from the fetuses of 1324 normal pregnant women. Weekly mean values and the standard deviations (S.D. ) were calculated for both BPD and FL from 12 to 40 weeks of pregnancy. Comparison was also made between our results and previous Western studies using t-test analysis. RESULTS Iranian fetuses had smaller BPD and shorter FL measurements in comparison with Western studies (P<0.05). There is a lag in BPD growth of our fetuses. The lag in FL growth is even more than BPD. Growth of the BPD and FL showed an asymptotic curve like that of Western studies but both of our values were lower. CONCLUSION Ethnicity may influence ultrasonic fetal biometric measurements.