1Postgraduate, Department of Obstetrics and Gynaecology, Sree Balaji Medical College and Hospital (SBMCH), Bharath Institute of Higher Education and Research (BIHER), Chennai, Tamil Nadu, India. Email: mukkusindhujareddy@gmail.com
2*Professor and Head of Department, Department of Obstetrics and Gynaecology, Sree Balaji Medical College and Hospital (SBMCH), Bharath Institute of Higher Education and Research (BIHER), Chennai, Tamil Nadu, India. Email: meenats@gmail.com
3Senior Resident, Department of Obstetrics and Gynaecology, Sree Balaji Medical College and Hospital (SBMCH), Bharath Institute of Higher Education and Research (BIHER), Chennai, Tamil Nadu, India. Email: afraakokan26@gmail.com
Background: Accurate antenatal estimation of fetal weight is critical for intrapartum decision-making and optimisation of maternal and neonatal outcomes. Both clinical and ultrasonographic methods are routinely employed in term pregnancies; however, their comparative accuracy and the influence of maternal determinants remain variable across populations. This study aimed to compare the accuracy of clinical and ultrasonographic fetal weight estimation with actual birth weight and to identify maternal factors associated with estimation errors.
Methods: This prospective comparative observational study was conducted at a tertiary care center over six months and included 100 term pregnant women with singleton, cephalic presentations. Clinical fetal weight estimation was performed using Johnson's formula based on symphysio-fundal height and fetal head station. Ultrasonographic estimation was derived from standard biometric parameters using Hadlock regression models (Hadlock-IV for primary analysis). Actual birth weight measured within 30 minutes of delivery served as the reference standard. Accuracy was defined as estimation within ±10% of actual birth weight. Associations between estimation accuracy and maternal factors were assessed using univariate and multivariate logistic regression analysis.
Results: The mean actual birth weight was 3140 ± 405 g. Clinical estimation yielded a mean weight of 3045 ± 410 g, demonstrating a statistically significant underestimation of 95 g (p = 0.041). Ultrasonographic estimation showed a mean weight of 3118 ± 395 g, with a non-significant mean difference of −22 g (p = 0.318). Accuracy within ±10% of actual birth weight was 90% for clinical estimation and 94% for ultrasonography. On multivariate analysis, maternal BMI ≥25 kg/m² (AOR 2.41; 95% CI 1.01–5.74; p = 0.048) and gestational diabetes mellitus (AOR 3.02; 95% CI 1.12–8.14; p = 0.029) were independently associated with inaccurate clinical fetal weight estimation.
Conclusion: Ultrasonographic fetal weight estimation demonstrates superior agreement with actual birth weight compared to clinical estimation in term pregnancies. Although clinical methods show acceptable overall accuracy, maternal obesity and gestational diabetes mellitus significantly reduce their reliability. Targeted ultrasonographic assessment in high-risk maternal subgroups may enhance intrapartum decision-making and perinatal preparedness.
Keywords: Fetal Weight; Birth Weight; Ultrasonography, Prenatal; Fundal Height; Pregnancy, Term; Gestational Diabetes Mellitus; Body Mass Index; Logistic Models; Obstetrics.
How to cite this article: Sindhuja M, Meena TS, Afraa S. A Comparative Study on the Accuracy of Clinical and Ultrasonographic Fetal Weight Estimation and Their Association with Maternal Secondary Determinants. Int J Drug Deliv Technol. 2026;16(15s): 578-587. DOI: 10.25258/ijddt.16.15s.68
Source of support: Nil.
Conflict of interest: None