Clinical Significance and Variations of Fetal Frontomaxillary Facial Angle Measurement in North Indian Pregnant Females

Objective: This study aims to establish normative reference ranges for FMF angle measurements in North Indian fetuses during first trimester (11-13+6 weeks of gestation) and assess its clinical significance. Design: A prospective observational study was conducted at GSVM Medical College, Kanpur, involving 161 North Indian pregnant females. Methods: Transabdominal ultrasound measurements of FMF angle were obtained using standardized mid-sagittal imaging techniques. The relationship between FMF angle and crown-rump length (CRL), gestational age, and maternal factors was analyzed using statistical models. Results: The mean FMF angle was 83.90° (SD = 1.76°), with a range of 80.0° to 87.3°. A strong inverse correlation was observed between FMF angle and CRL (r = -0.789, p <.001), confirming a gestational age-dependent decline. No significant influence of maternal age (p =.574) or gravida status (p =.233) was found on FMF angle measurements. The 5th to 95th percentile reference range for FMF angle was established as 81.3° to 86.5°, providing a clinically relevant baseline for North Indian populations. Conclusion: FMF angle is a stable and reproducible prenatal screening parameter in North Indian pregnancies. The study establishes normative data essential for refining regional first- trimester screening protocols and improving early detection of fetal anomalies.