Study of Precision of Humeral and Femur Lengths in Determining Gestational Age

Abstract

Introduction:Accurate estimation of gestational age (GA) is critical for fetal growth monitoring and obstetric decision-making. While conventional biometric parameters such as crown-rump length (CRL), biparietal diameter (BPD), and abdominal girth (AG) are routinely used, long bone measurements—particularly femur and humerus lengths—have emerged as reliable adjuncts in fetal age assessment.

Aim:To evaluate the precision of humeral and femur lengths in estimating gestational age and compare their correlation with other standard biometric parameters.

Materials and Methods:A cross-sectional study was conducted on 40 fetuses between 13 and 32 weeks of gestation. Biometric measurements including foot length, femur length, humerus length, CRL, BPD, and AG were recorded bilaterally. Data were stratified by gestational age and sex. Pearson correlation coefficients were calculated to assess the strength of association between each parameter and gestational age.

Results:All biometric parameters showed strong positive correlations with gestational age. Femur length (r = 0.997), humerus length (r = 0.996), and foot length (r = 0.998) demonstrated high predictive accuracy (P < 0.0001). CRL, BPD, and AG also showed comparable correlation values. Minimal gender-based differences were observed, with no significant impact on correlation strength.

Conclusion:Humerus and femur lengths are highly reliable indicators of gestational age, comparable to conventional parameters. Their integration into routine fetal biometric profiling may enhance precision in prenatal age estimation, particularly in mid-gestation and in cases of limited femoral visualization.