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Urinary incontinence and pelvic organ prolapse associated with pregnancy and childbirth


Pelvic floor disorders (PFDs) include pelvic organ prolapse, urinary incontinence, and fecal incontinence. The burden of disease related to PFDs is substantial. These disorders affect one-third of adult women in the United States, with considerable impact on their quality of life [1-4]. As many as 12 percent of women undergo surgical treatment for PFDs and approximately 17 percent of these women require reoperation [5-7]. The scope of this clinical issue is even greater than the surgical treatment rate suggests, because many women are managed conservatively with pessaries, pads, or no therapy.

An area of intense investigation is the effect of pregnancy and childbirth on a woman's risk of developing PFDs and whether this risk can be reduced by modifications to obstetric care. Some women have requested cesarean delivery for this reason.

This review will focus on urinary incontinence and pelvic organ prolapse. The data are more comprehensive for incontinence, because prolapse is difficult to study [8]. Many women with prolapse are asymptomatic and measurement of the true prolapse rate requires pelvic examination. Measurement of symptomatic prolapse is more clinically relevant, since asymptomatic prolapse does not require treatment. Even this presents a research challenge because prolapse symptoms may take longer to develop than symptoms of incontinence and the symptoms (eg, vaginal bulge or pressure, urinary retention, constipation) are less specific. Thus, even symptomatic prolapse is not well measured by symptom questionnaires [9]. Further, use of surgery as a surrogate measure for the prevalence of prolapse does not detect the number of women with symptomatic prolapse who have not had surgical treatment [10-12].

The association of urinary incontinence and pelvic organ prolapse with pregnancy and childbirth and selected management issues are reviewed here. The role of pregnancy and childbirth in the development of fecal incontinence is discussed separately. (See "Fecal incontinence associated with pregnancy and childbirth".)

General principles of the diagnosis and treatment of urinary incontinence and pelvic organ prolapse are also discussed separately. (See "Approach to women with urinary incontinence" and "Treatment and prevention of urinary incontinence in women" and "An overview of the epidemiology, risk factors, clinical manifestations, and management of pelvic organ prolapse in women" and "Pelvic organ prolapse in women: Diagnostic evaluation".)


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Literature review current through: Nov 2014. | This topic last updated: Sep 30, 2014.
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  1. Lukacz ES, Lawrence JM, Contreras R, et al. Parity, mode of delivery, and pelvic floor disorders. Obstet Gynecol 2006; 107:1253.
  2. Varma MG, Brown JS, Creasman JM, et al. Fecal incontinence in females older than aged 40 years: who is at risk? Dis Colon Rectum 2006; 49:841.
  3. Boreham MK, Richter HE, Kenton KS, et al. Anal incontinence in women presenting for gynecologic care: prevalence, risk factors, and impact upon quality of life. Am J Obstet Gynecol 2005; 192:1637.
  4. Fultz NH, Burgio K, Diokno AC, et al. Burden of stress urinary incontinence for community-dwelling women. Am J Obstet Gynecol 2003; 189:1275.
  5. Fialkow MF, Newton KM, Lentz GM, Weiss NS. Lifetime risk of surgical management for pelvic organ prolapse or urinary incontinence. Int Urogynecol J Pelvic Floor Dysfunct 2008; 19:437.
  6. Clark AL, Gregory T, Smith VJ, Edwards R. Epidemiologic evaluation of reoperation for surgically treated pelvic organ prolapse and urinary incontinence. Am J Obstet Gynecol 2003; 189:1261.
  7. Olsen AL, Smith VJ, Bergstrom JO, et al. Epidemiology of surgically managed pelvic organ prolapse and urinary incontinence. Obstet Gynecol 1997; 89:501.
  8. Barber MD, Maher C. Epidemiology and outcome assessment of pelvic organ prolapse. Int Urogynecol J 2013; 24:1783.
  9. Handa VL, Blomquist JL, Knoepp LR, et al. Pelvic floor disorders 5-10 years after vaginal or cesarean childbirth. Obstet Gynecol 2011; 118:777.
  10. Leijonhufvud Å, Lundholm C, Cnattingius S, et al. Risk of surgically managed pelvic floor dysfunction in relation to age at first delivery. Am J Obstet Gynecol 2012; 207:303.e1.
  11. Mant J, Painter R, Vessey M. Epidemiology of genital prolapse: observations from the Oxford Family Planning Association Study. Br J Obstet Gynaecol 1997; 104:579.
  12. Larsson C, Källen K, Andolf E. Cesarean section and risk of pelvic organ prolapse: a nested case-control study. Am J Obstet Gynecol 2009; 200:243.e1.
  13. Percy JP, Neill ME, Swash M, Parks AG. Electrophysiological study of motor nerve supply of pelvic floor. Lancet 1981; 1:16.
  14. Snooks SJ, Setchell M, Swash M, Henry MM. Injury to innervation of pelvic floor sphincter musculature in childbirth. Lancet 1984; 2:546.
  15. Allen RE, Hosker GL, Smith AR, Warrell DW. Pelvic floor damage and childbirth: a neurophysiological study. Br J Obstet Gynaecol 1990; 97:770.
  16. Snooks SJ, Swash M, Henry MM, Setchell M. Risk factors in childbirth causing damage to the pelvic floor innervation. Int J Colorectal Dis 1986; 1:20.
  17. Wang G, Lin G, Zhang H, et al. Effects of prolonged vaginal distension and β-aminopropionitrile on urinary continence and urethral structure. Urology 2011; 78:968.e13.
  18. Kerns JM, Damaser MS, Kane JM, et al. Effects of pudendal nerve injury in the female rat. Neurourol Urodyn 2000; 19:53.
  19. Pan HQ, Kerns JM, Lin DL, et al. Dual simulated childbirth injury delays anatomic recovery. Am J Physiol Renal Physiol 2009; 296:F277.
  20. Griffin KM, O'Herlihy C, O'Connell PR, Jones JF. Combined ischemic and neuropathic insult to the anal canal in an animal model of obstetric-related trauma. Dis Colon Rectum 2012; 55:32.
  21. Lin YH, Liu G, Li M, et al. Recovery of continence function following simulated birth trauma involves repair of muscle and nerves in the urethra in the female mouse. Eur Urol 2010; 57:506.
  22. Snooks SJ, Swash M, Mathers SE, Henry MM. Effect of vaginal delivery on the pelvic floor: a 5-year follow-up. Br J Surg 1990; 77:1358.
  23. Gilpin SA, Gosling JA, Smith AR, Warrell DW. The pathogenesis of genitourinary prolapse and stress incontinence of urine. A histological and histochemical study. Br J Obstet Gynaecol 1989; 96:15.
  24. Smith AR, Hosker GL, Warrell DW. The role of partial denervation of the pelvic floor in the aetiology of genitourinary prolapse and stress incontinence of urine. A neurophysiological study. Br J Obstet Gynaecol 1989; 96:24.
  25. Ashton-Miller JA, Delancey JO. On the biomechanics of vaginal birth and common sequelae. Annu Rev Biomed Eng 2009; 11:163.
  26. DeLancey JO, Morgan DM, Fenner DE, et al. Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse. Obstet Gynecol 2007; 109:295.
  27. Dietz HP, Simpson JM. Levator trauma is associated with pelvic organ prolapse. BJOG 2008; 115:979.
  28. Lien KC, Mooney B, DeLancey JO, Ashton-Miller JA. Levator ani muscle stretch induced by simulated vaginal birth. Obstet Gynecol 2004; 103:31.
  29. DeLancey JO, Kearney R, Chou Q, et al. The appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery. Obstet Gynecol 2003; 101:46.
  30. Albrich SB, Laterza RM, Skala C, et al. Impact of mode of delivery on levator morphology: a prospective observational study with three-dimensional ultrasound early in the postpartum period. BJOG 2012; 119:51.
  31. Shek KL, Dietz HP. Intrapartum risk factors for levator trauma. BJOG 2010; 117:1485.
  32. Kearney R, Miller JM, Ashton-Miller JA, DeLancey JO. Obstetric factors associated with levator ani muscle injury after vaginal birth. Obstet Gynecol 2006; 107:144.
  33. Chen L, Ashton-Miller JA, Hsu Y, DeLancey JO. Interaction among apical support, levator ani impairment, and anterior vaginal wall prolapse. Obstet Gynecol 2006; 108:324.
  34. Parente MP, Jorge RM, Mascarenhas T, et al. Deformation of the pelvic floor muscles during a vaginal delivery. Int Urogynecol J Pelvic Floor Dysfunct 2008; 19:65.
  35. Dietz HP, Simpson JM. Does delayed child-bearing increase the risk of levator injury in labour? Aust N Z J Obstet Gynaecol 2007; 47:491.
  36. Dietz HP, Kirby A, Shek KL, Bedwell PJ. Does avulsion of the puborectalis muscle affect bladder function? Int Urogynecol J Pelvic Floor Dysfunct 2009; 20:967.
  37. Friedman S, Blomquist JL, Nugent JM, et al. Pelvic muscle strength after childbirth. Obstet Gynecol 2012; 120:1021.
  38. Röckner G, Jonasson A, Olund A. The effect of mediolateral episiotomy at delivery on pelvic floor muscle strength evaluated with vaginal cones. Acta Obstet Gynecol Scand 1991; 70:51.
  39. Sartore A, De Seta F, Maso G, et al. The effects of mediolateral episiotomy on pelvic floor function after vaginal delivery. Obstet Gynecol 2004; 103:669.
  40. Hilde G, Stær-Jensen J, Siafarikas F, et al. Postpartum pelvic floor muscle training and urinary incontinence: a randomized controlled trial. Obstet Gynecol 2013; 122:1231.
  41. Richardson AC, Lyon JB, Williams NL. A new look at pelvic relaxation. Am J Obstet Gynecol 1976; 126:568.
  42. Delancey JO. Fascial and muscular abnormalities in women with urethral hypermobility and anterior vaginal wall prolapse. Am J Obstet Gynecol 2002; 187:93.
  43. Rahn DD, Ruff MD, Brown SA, et al. Biomechanical properties of the vaginal wall: effect of pregnancy, elastic fiber deficiency, and pelvic organ prolapse. Am J Obstet Gynecol 2008; 198:590.e1.
  44. Connell KA. Elastogenesis in the vaginal wall and pelvic-organ prolapse. N Engl J Med 2011; 364:2356.
  45. Goepel C, Johanna Kantelhardt E, Karbe I, et al. Changes of glycoprotein and collagen immunolocalization in the uterine artery wall of postmenopausal women with and without pelvic organ prolapse. Acta Histochem 2011; 113:375.
  46. Chen B, Wen Y, Zhang Z, et al. Microarray analysis of differentially expressed genes in vaginal tissues from women with stress urinary incontinence compared with asymptomatic women. Hum Reprod 2006; 21:22.
  47. O'Boyle AL, Woodman PJ, O'Boyle JD, et al. Pelvic organ support in nulliparous pregnant and nonpregnant women: a case control study. Am J Obstet Gynecol 2002; 187:99.
  48. Hendrix SL, Clark A, Nygaard I, et al. Pelvic organ prolapse in the Women's Health Initiative: gravity and gravidity. Am J Obstet Gynecol 2002; 186:1160.
  49. Handa VL, Garrett E, Hendrix S, et al. Progression and remission of pelvic organ prolapse: a longitudinal study of menopausal women. Am J Obstet Gynecol 2004; 190:27.
  50. Rortveit G, Hannestad YS, Daltveit AK, Hunskaar S. Age- and type-dependent effects of parity on urinary incontinence: the Norwegian EPINCONT study. Obstet Gynecol 2001; 98:1004.
  51. Abramov Y, Sand PK, Botros SM, et al. Risk factors for female anal incontinence: new insight through the Evanston-Northwestern twin sisters study. Obstet Gynecol 2005; 106:726.
  52. Goldberg RP, Abramov Y, Botros S, et al. Delivery mode is a major environmental determinant of stress urinary incontinence: results of the Evanston-Northwestern Twin Sisters Study. Am J Obstet Gynecol 2005; 193:2149.
  53. Subak LL, Waetjen LE, van den Eeden S, et al. Cost of pelvic organ prolapse surgery in the United States. Obstet Gynecol 2001; 98:646.
  54. Carley ME, Turner RJ, Scott DE, Alexander JM. Obstetric history in women with surgically corrected adult urinary incontinence or pelvic organ prolapse. J Am Assoc Gynecol Laparosc 1999; 6:85.
  55. Moalli PA, Jones Ivy S, Meyn LA, Zyczynski HM. Risk factors associated with pelvic floor disorders in women undergoing surgical repair. Obstet Gynecol 2003; 101:869.
  56. Chiaffarino F, Chatenoud L, Dindelli M, et al. Reproductive factors, family history, occupation and risk of urogenital prolapse. Eur J Obstet Gynecol Reprod Biol 1999; 82:63.
  57. Rinne KM, Kirkinen PP. What predisposes young women to genital prolapse? Eur J Obstet Gynecol Reprod Biol 1999; 84:23.
  58. MacLennan AH, Taylor AW, Wilson DH, Wilson D. The prevalence of pelvic floor disorders and their relationship to gender, age, parity and mode of delivery. BJOG 2000; 107:1460.
  59. Samuelsson EC, Victor FT, Tibblin G, Svärdsudd KF. Signs of genital prolapse in a Swedish population of women 20 to 59 years of age and possible related factors. Am J Obstet Gynecol 1999; 180:299.
  60. Patel DA, Xu X, Thomason AD, et al. Childbirth and pelvic floor dysfunction: an epidemiologic approach to the assessment of prevention opportunities at delivery. Am J Obstet Gynecol 2006; 195:23.
  61. Brown JS, Grady D, Ouslander JG, et al. Prevalence of urinary incontinence and associated risk factors in postmenopausal women. Heart & Estrogen/Progestin Replacement Study (HERS) Research Group. Obstet Gynecol 1999; 94:66.
  62. Nygaard I. Urinary incontinence: is cesarean delivery protective? Semin Perinatol 2006; 30:267.
  63. Nygaard I, Barber MD, Burgio KL, et al. Prevalence of symptomatic pelvic floor disorders in US women. JAMA 2008; 300:1311.
  64. O'Halloran T, Bell RJ, Robinson PJ, Davis SR. Urinary incontinence in young nulligravid women: a cross-sectional analysis. Ann Intern Med 2012; 157:87.
  65. Burgio KL, Zyczynski H, Locher JL, et al. Urinary incontinence in the 12-month postpartum period. Obstet Gynecol 2003; 102:1291.
  66. Viktrup L, Lose G. Lower urinary tract symptoms 5 years after the first delivery. Int Urogynecol J Pelvic Floor Dysfunct 2000; 11:336.
  67. Wesnes SL, Rortveit G, Bø K, Hunskaar S. Urinary incontinence during pregnancy. Obstet Gynecol 2007; 109:922.
  68. Boyles SH, Li H, Mori T, et al. Effect of mode of delivery on the incidence of urinary incontinence in primiparous women. Obstet Gynecol 2009; 113:134.
  69. Solans-Domènech M, Sánchez E, Espuña-Pons M, Pelvic Floor Research Group (Grup de Recerca del Sòl Pelvià; GRESP). Urinary and anal incontinence during pregnancy and postpartum: incidence, severity, and risk factors. Obstet Gynecol 2010; 115:618.
  70. Viktrup L, Lose G. The risk of stress incontinence 5 years after first delivery. Am J Obstet Gynecol 2001; 185:82.
  71. Thorp JM Jr, Norton PA, Wall LL, et al. Urinary incontinence in pregnancy and the puerperium: a prospective study. Am J Obstet Gynecol 1999; 181:266.
  72. van Brummen HJ, Bruinse HW, van der Bom JG, et al. How do the prevalences of urogenital symptoms change during pregnancy? Neurourol Urodyn 2006; 25:135.
  73. van Brummen HJ, Bruinse HW, van de Pol G, et al. Bothersome lower urinary tract symptoms 1 year after first delivery: prevalence and the effect of childbirth. BJU Int 2006; 98:89.
  74. Mason L, Glenn S, Walton I, Appleton C. The prevalence of stress incontinence during pregnancy and following delivery. Midwifery 1999; 15:120.
  75. Hansen BB, Svare J, Viktrup L, et al. Urinary incontinence during pregnancy and 1 year after delivery in primiparous women compared with a control group of nulliparous women. Neurourol Urodyn 2012; 31:475.
  76. Foldspang A, Hvidman L, Mommsen S, Nielsen JB. Risk of postpartum urinary incontinence associated with pregnancy and mode of delivery. Acta Obstet Gynecol Scand 2004; 83:923.
  77. Viktrup L, Lose G, Rolff M, Barfoed K. The symptom of stress incontinence caused by pregnancy or delivery in primiparas. Obstet Gynecol 1992; 79:945.
  78. Farrell SA, Allen VM, Baskett TF. Parturition and urinary incontinence in primiparas. Obstet Gynecol 2001; 97:350.
  79. Stainton MC, Strahle A, Fethney J. Leaking urine prior to pregnancy: a risk factor for postnatal incontinence. Aust N Z J Obstet Gynaecol 2005; 45:295.
  80. O'Boyle AL, O'Boyle JD, Ricks RE, et al. The natural history of pelvic organ support in pregnancy. Int Urogynecol J Pelvic Floor Dysfunct 2003; 14:46.
  81. Sze EH, Sherard GB 3rd, Dolezal JM. Pregnancy, labor, delivery, and pelvic organ prolapse. Obstet Gynecol 2002; 100:981.
  82. O'Boyle AL, O'Boyle JD, Calhoun B, Davis GD. Pelvic organ support in pregnancy and postpartum. Int Urogynecol J Pelvic Floor Dysfunct 2005; 16:69.
  83. Brown SJ, Gartland D, Donath S, MacArthur C. Effects of prolonged second stage, method of birth, timing of caesarean section and other obstetric risk factors on postnatal urinary incontinence: an Australian nulliparous cohort study. BJOG 2011; 118:991.
  84. Gartland D, Donath S, MacArthur C, Brown SJ. The onset, recurrence and associated obstetric risk factors for urinary incontinence in the first 18 months after a first birth: an Australian nulliparous cohort study. BJOG 2012; 119:1361.
  85. Groutz A, Rimon E, Peled S, et al. Cesarean section: does it really prevent the development of postpartum stress urinary incontinence? A prospective study of 363 women one year after their first delivery. Neurourol Urodyn 2004; 23:2.
  86. Chin HY, Chen MC, Liu YH, Wang KH. Postpartum urinary incontinence: a comparison of vaginal delivery, elective, and emergent cesarean section. Int Urogynecol J Pelvic Floor Dysfunct 2006; 17:631.
  87. Casey BM, Schaffer JI, Bloom SL, et al. Obstetric antecedents for postpartum pelvic floor dysfunction. Am J Obstet Gynecol 2005; 192:1655.
  88. Fritel X, Fauconnier A, Levet C, Bénifla JL. Stress urinary incontinence 4 years after the first delivery: a retrospective cohort survey. Acta Obstet Gynecol Scand 2004; 83:941.
  89. Leijonhufvud A, Lundholm C, Cnattingius S, et al. Risks of stress urinary incontinence and pelvic organ prolapse surgery in relation to mode of childbirth. Am J Obstet Gynecol 2011; 204:70.e1.
  90. Gyhagen M, Bullarbo M, Nielsen TF, Milsom I. Prevalence and risk factors for pelvic organ prolapse 20 years after childbirth: a national cohort study in singleton primiparae after vaginal or caesarean delivery. BJOG 2013; 120:152.
  91. Gyhagen M, Bullarbo M, Nielsen TF, Milsom I. The prevalence of urinary incontinence 20 years after childbirth: a national cohort study in singleton primiparae after vaginal or caesarean delivery. BJOG 2013; 120:144.
  92. Gabbe SG, DeLee JB. The prophylactic forceps operation. 1920. Am J Obstet Gynecol 2002; 187:254; discussion 255.
  93. Krofta L, Otcenásek M, Kasíková E, Feyereisl J. Pubococcygeus-puborectalis trauma after forceps delivery: evaluation of the levator ani muscle with 3D/4D ultrasound. Int Urogynecol J Pelvic Floor Dysfunct 2009; 20:1175.
  94. Handa VL, Blomquist JL, McDermott KC, et al. Pelvic floor disorders after vaginal birth: effect of episiotomy, perineal laceration, and operative birth. Obstet Gynecol 2012; 119:233.
  95. Pomeroy RH. Shall we cut and reconstruct the perineum for every primipara? Transactions of the American Gynecol Assoc 1918; 43:201.
  96. Nugent F. The primiparous perineum after forceps delivery. Am J Obstet Gynecol 1935; 30:249.
  97. Aldridge AN, Watson P. Analysis of end-results of labor in primiparas after spontaneous versus prophylactic methods of delivery. Am J Obstet Gynecol 1935; 30:554.
  98. Hartmann K, Viswanathan M, Palmieri R, et al. Outcomes of routine episiotomy: a systematic review. JAMA 2005; 293:2141.
  99. Thom DH, Brown JS, Schembri M, et al. Parturition events and risk of urinary incontinence in later life. Neurourol Urodyn 2011; 30:1456.
  100. Boyle R, Hay-Smith EJ, Cody JD, Mørkved S. Pelvic floor muscle training for prevention and treatment of urinary and faecal incontinence in antenatal and postnatal women. Cochrane Database Syst Rev 2012; 10:CD007471.
  101. Schwertner-Tiepelmann N, Thakar R, Sultan AH, Tunn R. Obstetric levator ani muscle injuries: current status. Ultrasound Obstet Gynecol 2012; 39:372.
  102. Li X, Kruger JA, Nash MP, Nielsen PM. Anisotropic effects of the levator ani muscle during childbirth. Biomech Model Mechanobiol 2011; 10:485.
  103. American College of Obstetricians and Gynecologists. ACOG committee opinion no. 559: Cesarean delivery on maternal request. Obstet Gynecol 2013; 121:904.
  104. Borello-France D, Burgio KL, Richter HE, et al. Fecal and urinary incontinence in primiparous women. Obstet Gynecol 2006; 108:863.
  105. Hannah ME, Whyte H, Hannah WJ, et al. Maternal outcomes at 2 years after planned cesarean section versus planned vaginal birth for breech presentation at term: the international randomized Term Breech Trial. Am J Obstet Gynecol 2004; 191:917.
  106. National Institutes of Health state-of-the-science conference statement: Cesarean delivery on maternal request March 27-29, 2006. Obstet Gynecol 2006; 107:1386.
  107. Handa VL, Harvey L, Fox HE, Kjerulff KH. Parity and route of delivery: does cesarean delivery reduce bladder symptoms later in life? Am J Obstet Gynecol 2004; 191:463.
  108. Grodstein F, Fretts R, Lifford K, et al. Association of age, race, and obstetric history with urinary symptoms among women in the Nurses' Health Study. Am J Obstet Gynecol 2003; 189:428.
  109. Altman D, Ekström A, Gustafsson C, et al. Risk of urinary incontinence after childbirth: a 10-year prospective cohort study. Obstet Gynecol 2006; 108:873.
  110. Connolly TJ, Litman HJ, Tennstedt SL, et al. The effect of mode of delivery, parity, and birth weight on risk of urinary incontinence. Int Urogynecol J Pelvic Floor Dysfunct 2007; 18:1033.
  111. Swift SE. The distribution of pelvic organ support in a population of female subjects seen for routine gynecologic health care. Am J Obstet Gynecol 2000; 183:277.
  112. Hannestad YS, Rortveit G, Daltveit AK, Hunskaar S. Are smoking and other lifestyle factors associated with female urinary incontinence? The Norwegian EPINCONT Study. BJOG 2003; 110:247.
  113. Woodman PJ, Swift SE, O'Boyle AL, et al. Prevalence of severe pelvic organ prolapse in relation to job description and socioeconomic status: a multicenter cross-sectional study. Int Urogynecol J Pelvic Floor Dysfunct 2006; 17:340.
  114. Wesnes SL, Hunskaar S, Bo K, Rortveit G. The effect of urinary incontinence status during pregnancy and delivery mode on incontinence postpartum. A cohort study. BJOG 2009; 116:700.