Error Analysis for Determination of Accuracy of Johnson’s Formula, Dare’s Formula and Mother's Opinion for the Estimation of Birth Weight: Results of an Iranian Cross‐Sectional Study

• Main Authors: Alirezaei Somayeh, Azmoude Elham, Ghaderi Asma
• Format: Article
• Language: English
• Published: Sciendo 2018-12-01
• Series: Acta Facultatis Medicae Naissensis
• Subjects: fetal weight; birth weight; Iran
• Online Access: http://www.degruyter.com/view/j/afmnai.2018.35.issue-4/afmnai-2018-0034/afmnai-2018-0034.xml?format=INT

Accurate fetal weight estimation is important for the management of birth. According to the existing literature, none of the clinical techniques is superior to any other. This study aimed to compare error analysis for the determination of the accuracy of Johnson’s formula, Dare’s formula and mother's opinion for the estimation of birth weight. A cross-sectional study involving 147 full-term, cephalic, singleton pregnancies, was performed. The mother’s opinion was recorded and Johnson’s and Dare’s formulas were used to calculate the fetal weight. Accuracy was determined by percentage error, absolute percentage error, and proportion of estimates within 10% of actual birth-weight. Statistical analysis was done using the RM ANOVA, Friedman and Cochran. P < 0.05 was considered significant. The birth weight was correctly estimated in 34.7%, 58.5%, 66% of the cases using the mother’s estimate, Dare’s and Johnson’s formulas. Respectively the proportion of the mother's estimate and Dare’s formula was significantly lower than that of Johnson’s formula for all birth weights. No significant difference was observed in all the measures of accuracy for the low birth-weight range. The mean error of Johnson's formula in both normal weight and macrosomic groups was less than those obtained by the Dare's formula and mother's opinion. The Johnson’s formula is more accurate in actual birth weight estimation than the Dare ’s one and mother's opinion. In the normal weight range, Johnson’s formula is more accurate of the two, while in the macrosomic group, Dare’s formula appears to be more accurate.