The purpose of this study was to evaluate the morphological characteristics and related factors of changes to the female pelvic floor architecture during rest and the Valslva maneuver using three-dimensional (3D) transperineal ultrasonography (TPUS) in parous women.One hundred thirty-five premenopausal parous women (aged 29-50 years) were evaluated. The pelvic floor structures were measured during rest and during the Valsalva maneuver using 3D TPUS.The delivery mode was an im- portant affecting factor in determining the change of contractility of pelvic floor architecture. The factors of age and weight were asso- ciated with changes in the anus.The delivery mode might be a meaningful factor in the change of contractility of pelvic floor architecture. These measurements provide a baseline upon which further investigations in a larger cohort of subjects can be compared, to determine the range and change of the normal appearance of the specific pelvic structures.