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Research Article Volume 10 Issue 5
A comparative study between Johnson formula and Hadlock formula for estimating fetal weight in term gestation
Kavya Kota, Manchuru Aruna
Junior Resident, Department of Obstetrics and Gynaecology, JJM Medical College, India
Senior Resident, Department of Obstetrics and Gynaecology, JJM Medical College, India
Received: August 01, 2019 | Published: September 27, 2019
Citation: Kota K, Aruna M. A comparative study between Johnson formula and Hadlock formula for estimating fetal weight in term gestation. Obstet Gynecol Int J. 2019;10(5):355-359. DOI: 10.15406/ogij.2019.10.00466
Abstract
Background: Ultrasound study forms a very important tool in present day obstetrics. The accurate assessment of weight by ultrasound examinations is mandatory for obstetric management particularly at term.
Objective: To compare Johnson’s formula and Hadlock’s formula for estimating fetal weight in term gestation.
Materials and Methods: We performed a prospective observational study in 200 women. The estimated fetal weight (EFW) was measured at term by sonological formula i.e. Hadlock formula [Log10EFW=1.3596-0.00386 (AC x FL)+0.0064 (HC)+0.00061(BPD x AC)+0.0425 (AC)+0.174 (FL)] and Johnson’s formula [(Symphysio-fundal height (cms)-X) * 155] and compared with the actual birth weight. The statistical analysis was done using Z test.
Results: The mean birth weight of Hadlock formula is closest to the mean of actual birth weight when compared to that of Johnson’s formula. P value obtained for both the formulae were <0.01, highly significant. The mean error of the Hadlock formula was 188 grams and the mean error of Johnson formula was 202.148 grams. The percentile error of <20% was 77% in Hadlock formula compared to 79% in Johnson’s formula.
Conclusion: The mean birth weight of hadlock formula was closest to the mean of actual birth weight when compared to Johnson’s formula. The least mean error was noted in the birth weight between 2.5-3.5Kg. Johnson’s formula overestimated the weight in SGA fetuses and Hadlock formula underestimated the weight in LGA fetus.
Keywords: Estimated fetal weight, Hadlock formula, Johnson’s formula, Ultrasound, Fetal growth retardation, Respiratory distress syndrome, Low birth weight, Abdominal girth, Maternal, Pregnancy, Head circumference, Femur length, Abdominal circumference, Anterior posterior trunk diameter, Transverse trunk diameter
©2019 Kota, et al. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially.