Abstract
Accurate estimation of gestational age (GA) is central to antenatal care because it informs fetal growth assessment, timing of obstetric interventions, counselling, and perinatal risk stratification. Although conventional ultrasonographic biometric parameters are widely used, their precision may decline in late gestation or in selected clinical circumstances. The fetal clavicle is the first bone to ossify and shows a measurable, progressive growth pattern during intrauterine life; therefore, it may provide an additional morphometric marker for GA estimation. Objective: To evaluate ultrasonographic morphogenesis of the fetal clavicle and assess the relationship between clavicular morphometric parameters and gestational age. This hospital-based cross-sectional study was conducted over 18 months in the Departments of Anatomy and Radiodiagnosis, Shyam Shah Medical College and Sanjay Gandhi Hospital, Rewa, Madhya Pradesh, India, after Institutional Ethics Committee approval. A total of 150 antenatal women with singleton, non-anomalous pregnancies between 14 and 42 weeks of gestation were examined using high-resolution ultrasonography. Clavicular length, acromial width, central width, sternal width, projection surface area, and clavicular volume were planned for assessment. Pearson correlation and linear regression were used to examine the relationship between clavicular measurements and gestational age. The receiver operating characteristic curve for identifying gestational age ≥28 weeks was treated as exploratory because threshold, sensitivity, specificity, and confidence interval values were not available in the dataset. The largest proportion of fetuses belonged to the 27-30-week gestational-age group (17.3%). Mean clavicular length increased steadily from 12.5 ± 1.8 mm at 14-18 weeks to 38.2 ± 3.9 mm at 39-42 weeks. Acromial width increased from 2.1 ± 0.4 mm to 5.3 ± 1.0 mm, central width from 1.8 ± 0.3 mm to 4.9 ± 0.9 mm, sternal width from 2.3 ± 0.4 mm to 5.8 ± 1.1 mm, and projection surface area from 35.2 ± 6.5 mm² to 198.5 ± 20.3 mm² across the same gestational interval. Clavicular length showed a very strong positive correlation with GA (r = 0.982, p < 0.001). Linear regression yielded the equation GA (weeks) = 6.12 + 0.92 x clavicular length (mm), with R² = 0.964. Fetal clavicular morphogenesis showed a consistent and statistically significant increase with advancing gestation. Clavicular length demonstrated a very strong association with gestational age and may serve as a simple, non-invasive adjunct to standard fetal biometric indices, particularly when conventional measurements are inconclusive. Use of clavicular length as a stand-alone dating parameter requires external validation and formal reproducibility assessment.
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