Relation Between Vaginal Birth and Pelvic Organ Prolapse

Abstract

The major etiologic factor predisposing women to develop pelvic organ prolapse is generally believed to be vaginal birth. Prolapse descending within or at the vaginal introitus occurs more frequently in multiparas than nulliparas, but it is unclear whether multiparas have more defects that protrude outside the vaginal introitus. Whether the prevalence of pelvic organ prolapse increases with each additional vaginal birth is also unclear. This prospective cross-sectional study compared pelvic organ prolapse quantification (POPQ) stages III and IV prolapse among 458 nulliparas and 892 multiparas in order to determine whether term vaginal birth was associated with an increase in pelvic support defect protruding outside the vaginal introitus. The study also determined whether each additional vaginal birth was associated with increased pelvic organ prolapse by comparing the difference in POPQ stage distribution between nulliparas and multiparas having one (n = 272), two (n = 299), and at least three term vaginal deliveries (n = 321). Multiple ordinal logistic regression was used to analyze POPQ stage as an ordinal variable (POPQ stage 0–I, II, and III–IV). Following adjustments for all covariates, in comparison with nulliparas, the odds ratio (OR) of having POPQ stage II defect associated with multiparas was 2.95, with a 95% confidence interval [CI] of 2.06–4.24), whereas the OR of having POPQ stages III or higher prolapse associated with multiparas was 1.01 (95% CI, 0.40–2.79). The prevalence of POPQ stage II defect was 25% in nulliparous women and 50%, 66%, and 69%, respectively, in multiparas women with one, two, and at least three term vaginal deliveries (P < 0.001). Only a minimal increase in POPQ stage II pelvic support defect was found with subsequent births. No parity difference was found for the prevalence of POPQ stage III or IV prolapse (P = 0.618). There was an age-related change associated with POPQ stage II pelvic support defect as well as with stages III and IV defects. The investigators conclude from these findings that vaginal birth is not the major etiologic factor predisposing women to develop POPQ stages III and IV pelvic organ prolapse. Unlike vaginal birth, age-related change may be an important risk factor for stage III and IV prolapse.