Measurement of fetal maxillary and mandibular angles for first-trimester prenatal screening among Taiwanese women

Background: Early fetal structure evaluation is crucial. Fetal abnormalities might indicate chromosomal anomalies or abnormal fetal growth. The aim of this study was to establish the appropriate reference range of maxillary and mandibular angles among the Taiwanese population at 11⁺⁰-13⁺⁶ weeks of gestation in normal singleton pregnancy as reference values for prenatal ultrasonographic examinations. Methods: Fetal ultrasonographic data on maxillary angles and mandibular angles at a gestational age ranging from 11⁺⁰ weeks to 13⁺⁶ weeks were recorded in this study. Maternal background and pregnancy outcome were obtained from hospital records. Results: A total of 87 patients were included in this study. Maxillary and mandibular angles were successfully recorded in 87 (100%) and 84 (96.6%) patients, respectively. The mean maternal age was 31 (range, 19-41) years, with a corresponding gestational age of 12⁺⁴ (range, 11⁺⁰-13⁺⁶) weeks. The maxillary and mandibular angles were 79.9° ± 15.6° and 71.0° ± 12.8°, respectively. First-degree correlation was not found to exist between gestational age and maxillary and mandibular angles. Conclusion: Normative data for ultrasonographic measurements of maxillary and mandibular angles among the Taiwanese population are presented. Our results may serve as reference values in congenital anomaly screening during prenatal examination.