Supplementary Material for: Longitudinal Changes of Subpubic Arch Angle throughout Pregnancy

<b><i>Objective:</i></b> The objective of this study is to assess whether the subpubic arch angle (SPA) changes throughout pregnancy. <b><i>Materials and Methods:</i></b> We recruited a group of nulliparous women in the first trimester of pregnancy. Each woman was assessed 3 times throughout pregnancy, once per each trimester, by measuring SPA using a recently described highly reproducible three-dimensional transperineal ultrasound (linear reconstruction with contrast enhancement technique; OmniView-volume contrast imaging). Repeated measures analysis of variance was used to study SPA changes during pregnancy. <b><i>Results:</i></b> Overall, 97 women were included in the final analysis. SPA increased progressively and significantly (<i>F</i> = 27.824, <i>p</i> &lt; 0.001) from the first to the second trimester (121.8 ± 8.7 vs. 123.5 ± 8.4°, <i>p</i> = 0.01) and from the second to the third trimester (123.5 ± 8.4 vs. 125.3 ± 8.1°, <i>p</i> = 0.01). <b><i>Conclusion:</i></b> SPA width increases progressively but slightly during pregnancy. Although this finding is interesting, the extremely small difference detected is unlikely to be clinically significant.