Sexual dimorphism of the fetal ilium: a 3D geometric morphometric approach with multislice computed tomography

Adult sexual dimorphism is well established. However, data regarding fetuses are sparse with contradictory results. Our study aimed to look for fetal sexual dimorphism. Multislice computed tomography (MSCT) examinations and three-dimensional (3D) reconstructions were recorded on 93 fetal iliac bones aged between 21 and 40 weeks of amenorrhea (WA). The collection was divided into two age groups, with a cutoff at 30 WA. The 3D geometric morphometric analysis was based on outline analysis. We used elliptic Fourier analysis (EFA) because of the difficulty of landmark positioning. Step-by-step reconstructions allowed a better comprehension of the fine shape details. Principal component analysis (PCA) and linear discriminant analysis (LDA) were performed on the two age groups. Results did not show any difference between male and female shapes, in both age groups. We demonstrate the feasibility of outline analysis for immature shapes, but sexual dimorphism has not been established in our collection.