Changes in levator hiatus dimensions during pregnancy and after delivery in nulliparas: a prospective cohort study using 3D transperineal ultrasound.

Purpose: The purpose of this study was to investigate the changes that occur in the levator ani muscle (1) during pregnancy and (2) after labor depending on the mode of delivery in a cohort of nulliparas.

Materials And Methods: A prospective cohort longitudinal study, consisting of 84 primiparas who were examined and recruited in an antenatal clinic was conducted. All participants were submitted to a real-time three-dimensional (3D) ultrasonographic evaluation of the levator ani at (1) 12, (2) 22, and (3) 32 weeks of pregnancy (4) and 4-6 months postdelivery.