Pregnancy, labour and delivery as risk factors for pelvic organ prolapse: a systematic review

Introduction Pregnancy and childbirth are considered risk factors for pelvic organ prolapse (POP). The long latency between obstetric events and morbidity hinders the establishment of cause-effect relationships. Recently, intermediate outcomes such as organ descent and levator avulsion (LA) have been identified. We aimed to assess the effect of obstetric events on symptoms and signs of POP and on LA. Methods We systematically reviewed the literature by searching PubMed/MEDLINE, Embase and Cochrane Library. We included studies in women examining associations between obstetric events and symptoms and signs of POP and LA, assessed through questionnaires, clinical examination and pelvic floor imaging. Two reviewers evaluated the studies for eligibility and for methodological quality/susceptibility to bias. We extracted study results and clustered them by outcome: symptoms of POP (sPOP), clinical findings of POP (cPOP) and LA. When appropriate, we performed a random-effect meta-analysis and reported the summary odds ratios (OR) with 95% confidence intervals. Heterogeneity across studies was assessed using the I-2 statistic. Results The first vaginal delivery was a risk factor for POP as measured by sPOP (OR: 2.65 [1.81-3.88]), cPOP (OR: 4.85 [2.15-10.94]) and in association with LA (OR: 41.6 [4.13- 419.41]). Forceps delivery was a risk factor for POP as measured by sPOP (OR: 2.51 [1.34-4.69]), cPOP (OR: 1.68 [1.21-2.34]) and in association with LA (OR: 5.92 [3.75-9.34]). Birth exclusively by caesarean was protective for sPOP (OR: 0.38 [0.29-0.51]) and for cPOP (OR: 0.29 [0.20-0.41]) and it did not confer any additional risk compared to nulliparity. Conclusions This review confirms a strong aetiological link between vaginal birth and POP, with the first vaginal and forceps delivery being the main determinants.