Background: Early determination of fetal gender during pregnancy is essential for the early detection of gender-linked diseases in the fetus. Thus, the purpose of this study was to evaluate the sensitivity and specificity of ultrasonography in determining fetal gender in pregnant mothers at 11 to 14 weeks of gestation. Methods: The study included 227 pregnant mothers at 11 to 14 weeks of gestational age. Ultrasonography results were recorded for fetal gender determination based on gestational age and body mass index (BMI). Results: The sensitivity and specificity of ultrasonography for male gender determination were 91.73% and 99.05%, respectively. This value for female gender determination was 99.05% and 91.73%, respectively. Conclusions: The results of our study showed that ultrasonography at 11 to 14 weeks of gestation had high sensitivity and specificity in detecting gender, and its sensitivity in female gender determination was higher.