Validation of a simple clinical formula for predicting birth weight in women who are in labour at term

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dc.contributor.author Tlale, Juliet Karabo
dc.date.accessioned 2012-04-02T11:03:15Z
dc.date.available 2012-04-02T11:03:15Z
dc.date.issued 2012-04-02
dc.identifier.uri http://hdl.handle.net/10539/11449
dc.description M.Med. (Obstetrics and Gynaecology), Faculty of Health Sciences, University of the Witwatersrand, 2011 en_ZA
dc.description.abstract Background Estimation of fetal weight during labour at term is frequently done to decide if there is a risk of cephalopelvic disproportion or shoulder dystocia. Estimation of fetal weight by clinical palpation has been shown to be as good as ultrasound in labour at term, giving estimates that are correct to within 10% of the birth weight in 60% to 70% of cases. Symphysis-fundal height (SFH) measurement may offer an easier method of fetal weight estimation, but no simple formula is currently available. The objective of this study was to validate a formula calculated from unpublished work done at Chris Hani Baragwanath hospital, where birth weight in g = 100 (SFH in cm – 5) for term intrapartum measurements. In that study, the formula gave estimates correct to within 10% of the birth weight in 67% of cases. Methods This was a prospective cross-sectional study done on women at term with singleton live cephalic presentations at the Charlotte Maxeke Johannesburg Academic Hospital and Chris Hani Baragwanath Hospital. All participants were in the active phase of the first stage of labour. The author performed abdominal palpation, and measured SFH twice, taking the average of the two measurements as the SFH. Maternal heights, weights, membrane status and level of the head were also recorded. The SFH measurements were transformed into estimated birth weights using the formula, and these were compared with the actual birth weights. 7 Results The researcher assessed 294 women, 289 of them being black African. The mean birth weight was 3221 g and the mean SFH was 37 cm, which equated to a mean estimated birth weight, using the formula, of 3200 g. Simple linear regression between SFH and birth weight gave a correlation coefficient (r) of 0.56. The mean percentage error in fetal weight estimation using the formula was 8.7%. Sixty-five per cent of estimations were found to fall within 10% of the actual birth weight. Fetal weight estimates were best (mean percentage error 6.8%) in the birth weight range of 3000 g to 3499 g, and worst at the extremes of term birth weight. Conclusion The birth weight formula was validated in this study, giving very similar results to those found in the original research that described the formula. The formula may be applied by clinicians in environments that serve populations similar to those that participated in this study. en_ZA
dc.language.iso en en_ZA
dc.subject.mesh Birth Weight en-US
dc.title Validation of a simple clinical formula for predicting birth weight in women who are in labour at term en_ZA
dc.type Thesis en_ZA


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    Thesis (Ph.D.)--University of the Witwatersrand, 1972.

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