Estimation of fetal weight in utero by Dawn's formula and Johnson's formula: a comparative study


  • Mallikarjuna M. Department of Obstetrics & Gynaecology, Subbaiah Institute of Medical Sciences, Shimoga, Karnataka, India
  • Rajeshwari B. V. Department of Obstetrics & Gynaecology, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Telangana, India



Birth weight, Johnson formula, Dawn formula


Background: Survival of the premature infant has been shown to be related more to fetal weight than to any other consideration. A lot of work has been done to find out accurate methods for estimation of fetal size and weight in utero.

Methods: This study consists of total 200 case studies included patient of different parity all delivered in these hospitals either vaginally or by caesarian section. Two methods of estimation of birth weight were assessed and compared.

Results: 33.5% of cases were within ±100gms by Johnson's formula, whereas in Dawn's formula 51.5% cases were within +100 gm of actual birth weight.73% of cases by Johnson's formula were within ±250 gms and 88.5% of cases by Dawn's formula were within ±250 gms of actual birth weight.91% of cases by Johnson's formula and 99% of cases by Dawn's formula were within ±500 gms of actual birth weight.

Conclusions: Dawn's formula was found to be more accurate (88.5% within ±250 gms) than Johnson's formula (53.5% within ±250 gms) in prediction of antenatal fetal weight.


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Original Research Articles