Fetal ultrasound parameters: Reference values for a local perspective

Abstract

Background: Fetal biometry, with the help of ultrasonography (USG) provides the most reliable and important information about fetal growth and well-being. Frequently used parameters for fetal measurements by this method are the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). These fetal dimensions depend upon the racial demographic characteristics, nutrition, genetics and many more environmental factors of a particular population. Aims: The purpose of the present investigation was to define and analyze these fetal biometric parameters in our local population and to compare them with the given norms. Methods: This cross-sectional study with convenience sampling was conducted on a total of 425 fetuses with a period of gestation between 18 to 38 weeks. Descriptive statistics was used to calculate the mean with standard deviation and 95% confidence interval (CI) for each fetal parameter in each gestational week. Results: Mean of BPD and FL in our population are similar to the mean values given by Hadlock throughout the pregnancy, except near the end of the third trimester where our population shows a slightly lower range of mean values. HC and AC fall below the lower range of Hadlock as early as 24 weeks of pregnancy. Conclusions: Fetal biometric parameters in the studied population are at the lower range of established nomograms by Hadlock on white fetuses, more so with the progression of pregnancy.

Keywords

• fetal-biometry
• gestational age
• hadlock standard reference charts
• ultrasound