Predicting birth weight using an index derived from symphysiofundal height, abdominal circumference and skin fold thickness in Mulago hospital parturients

Abstract

Background: Estimated intrapartum fetal weight impacts greatly on delivery decisions and outcome. Ultrasound is used worldwide to estimate fetal weight but is not readily accessible in developing countries. Clinical estimate by palpation is subjective, Symphysiofundal height measurement alone is not clinically significant, combining the latter with abdominal circumference and skin fold thickness hasn't been adequately evaluated but could provide an objective alternative for intrapartum fetal weight estimation. Objective: To determine if birth weight can be predicted Using an index derived from symphysiofundal height, abdominal circumference and skin fold thickness in parturients attending Mulago hospital general labor suites. Methods: Across sectional study was conducted in Mulago hospital general labor wards in Kampala-Uganda. Using consecutive sampling, 354 participants were recruited. Following the study procedures, Symphysiofundal height, abdominal circumference and skin fold thickness were taken in centimeters. Data on other co-variants was collected using a structured pretested questionnaire. Data was double entered into Epidata and exported to SPSS version 12. Auto correlation for co-variant factors, multiple linear regressions and step up stepwise model building were used. R2 statistic was computed and the best model was subjected to Bland - Altman plot for agreement. Results: The mean; age 23.7years, parity 2.3, birth weight 3114.4 grams. The best model was, Estimated fetal weight = -620.1 + 49.9 SFH + 23.6 AC - 102.4 T. R= 0.604, 95% CI (0.596-0.806), R 2= 0.365.Using Altman-Bland analysis; mean difference 3.99grams, 69.8% differences were within +/- two standard deviations of the mean difference. The 95% limits of agreement were (- 326.75- 334.7) grams. Conclusion: Using, Estimated fetal weight = -620.1 + 49.9 SFH + 23.6 AC - 102.4T, birth weight can be predicted from symphysiofundal height, abdominal circumference and skin fold thickness in Mulago hospital parturients, with 95% limits of agreement of (- 326.75- 334.7) grams and mean difference of 3.99 grams. Recommendations: In absence of ultrasound facilities for estimating fetal weight, the new formula could be used if validated by further studies.