Normal Fetal Biometry in Third Trimester Pregnancy of Healthy Yemeni Women

Abstract

OBJECTIVE : This research is an attempt to establish fetal ultrasound biometry charts for normal Yemeni fetuses between 28 - 40 weeks of gestation. METHOOD: Cross- sectional fetal ultrasound data of normal singleton pregnancies which had been preformed over a period of 6 months, where retrieved .Only pregnant Yemeni healthy women aged 20-35 years with certain last menstrual period dates were included. Each fetus contributed to only one set of data. The mean predictive values and standard deviations of normal ranges for biparietal diameter ( BPD ), head circumference ( HC ), abdominal circumference ( AC ),and femur length ( FL ) were calculated. The mean and 5th and 95th percentiles for each fetal biometry were established .Fetal charts with the raw data for each measurement with superimposed fitted lines derived from IV polynomial (quadratic) regression were constructed. Quadratic model showed good fit to the data during construction of fetal charts. RESULT : The new fetal measurement charts and new reference mean, 5th ,and 95th centile charts for BPD,HC,AC,and FL have been established and compared with previously published data emphasizes the presence of significant variation in fetal morphometric measurements overall these gestational weeks ( 28-40 ), they were clearly lower than those widely used charts ( hadlock charts ) . CONCLUSION : The clinical significance of this variation differs according to the primary objective of ultrasound fetal measurements. For estimation of fetal age , usually by head and femur measurements in third trimester seems to have limited significance . Whereas for estimation of fetal growth and / or weight, based on the abdominal circumference, the use of other population charts has the potential of either over-or under diagnosis of abnormal growth of fetuses. This showing the importance of racial differences between populations and elucidates the need to develop fetal biometries charts for each region.