Estimated Fetal Weight; A Comparison between Clinical and Ultrasonographical Measurements

  • Munazza Nasir Postgraduate Trainee, Obstetrics and Gynaecology, KRL Hospital, Islamabad
  • Irum Sohail Professor of Obstetrics and Gynaecology KRL General Hospital, Islamabad
  • Nazia Siraj Postgraduate Trainee, Obstetrics and Gynaecology, KRL Hospital, Islamabad
Keywords: Fetal weight, Fetal body weight, Birth weight


Objective: To determine which method (clinical or ultrasonogrpahic) is more accurate in the estimation of fetal weights by comparing these methods with actual birth weights
Methodology: It was a prospective and comparative study of 100 women at term gestation admitted in KRL General Hospital,Islamabad from July 2018 to Dec 2018. Patients of different parities at term were included.Their ultrasound scans for fetal weight were performed within last 1 week.Johnson’s formula and Dare’s formula were used for clinical method of fetal weight estimation.Hadlock’s formula was used for ultrasonographic estimation of fetal weight.A comparison between estimated and actual birth weights was made after delivery. All statistical data was analysed through Statistical Package for Social Sciences (SPSS) version 21 software.
Results: It was seen that <500g error was given by ultrasound in 77% of the participants,by Dare’s method in 57% and by Johnson’s method in 47 % participants. Ultrasound gave >1000g error in only 3% of patients, while Johnson’s and Dare’s formulae gave it in 15% of patients each. The average error given by ultrasound (361.36+277.78g) was significantly lower than by Johnson’s method (585.74+343.62g) and Dare’s method (521.52+370.86g). There was statistically significant difference between fetal weights estimated by clinical methods and actual birth weights (P value <0.001).There was no statistically significant difference between measurements by ultrasound scan and actual birth weights (P value= 0.289).
Conclusion: Fetal weight estimation by ultrasound scan is better than by clinical methods (Johnson’s and Dare’s methods). Among the clinical methods Dare’s method is more reliable than Johnson’s method in the estimation of fetal weight.

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