UROGYNECOLOGY Risks of stress urinary incontinence and pelvic organ prolapse surgery in relation to mode of childbirth Åsa Leijonhufvud, MD; Cecilia Lundholm, MSc; Sven Cnattingius, MD, PhD; Fredrik Granath, PhD; Ellika Andolf, MD, PhD; Daniel Altman, MD, PhD OBJECTIVE: To estimate the risk for stress urinary incontinence and pelvic organ prolapse surgery related to vaginal birth or cesarean delivery. STUDY DESIGN: A cohort study of all women having their first and all subsequent deliveries by cesarean (n = 33,167), and an age-matched sample of women only having vaginal deliveries (n = 63,229) between 1973 and 1983. Hazard ratios were calculated using Cox regression models with 95% confidence intervals. RESULTS: Women only having vaginal deliveries had increased overall risks of incontinence (hazard ratio, 2.9; 95% confidence interval, 2.4 – 3.6) and prolapse surgery (hazard ratio, 9.2; 95% confidence interval, 7.0 –12.1) compared with women only having cesarean deliveries. CONCLUSION: Having only vaginal childbirths was associated with a significantly increased risk of stress urinary incontinence and pelvic or- gan prolapse surgery later in life compared with only having cesarean deliveries. Key words: cesarean section, delivery, incontinence, prolapse Cite this article as: 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.e1-6. A lmost one-fifth of US women expe- rience symptoms of urinary incon- tinence or pelvic organ prolapse (POP). 1 Surgery remains the mainstay of treat- ment for both disorders, 2 and regional US studies estimate that the life time risk of having surgery for stress urinary in- continence (SUI) or POP is 11%. 3,4 Childbirth is widely considered an estab- lished risk factor for both SUI and POP and women rarely enter pregnancy with preexisting symptoms of either of these diseases. 5 In 2006, one third of all US childbirths were performed by cesarean deliveries, and an increasing proportion of cesarean deliveries are performed on maternal request (http://www.hcup-us. ahrq.gov/reports/statbriefs/sb71.pdf ). The reason for the rising incidence of elective cesarean deliveries performed on maternal request is multifactorial, 6 but may to some extent be driven by women’s apprehension for pelvic floor sequela after vaginal delivery. Vaginal childbirth may induce func- tional disorders of the lower urinary tract and pelvic floor as a consequence of deliv- ery trauma to pelvic organ neuromuscular function and morphology. 7-9 Although lit- tle is known about the long-term effects of cesarean delivery on POP, several epide- miologic studies suggest that cesarean delivery significantly decreases the risk for postpartum urinary incontinence. 10-12 However, prevention of disorders later in life by cesarean delivery is controversial. Cesarean delivery involves major surgery and studies suggest that the protective ef- fects of cesarean delivery on urinary incon- tinence diminishes over time and even dis- appears after multiple deliveries. 11,13 Whether cesarean delivery provides a long-lasting protection against SUI or POP surgery must be considered an un- resolved issue. The aim of this popula- tion-based cohort study was to compare long-term effects of vaginal vs cesarean delivery with respect to risks of urinary incontinence and POP surgery. MATERIALS AND METHODS The nationwide Swedish Medical Birth Register, kept by the National Board of Health and Welfare, contains prenatal, obstetric, and neonatal data from almost 99% of all women giving birth in Swed- ish hospitals from 1973 and thereafter (http://www.socialstyrelsen.se/register/ halsodataregister/medicinskafodelse registret/inenglish). Within the Medical Birth Register, we initially identified all women who gave birth to their first child by cesarean section and thereafter (if multiparous) only gave birth by cesarean section from January 1973 through De- cember 1982. To each woman in this ce- sarean delivery cohort, we randomly se- lected 2 control women, individually matched by year of birth, who gave birth to their first child by vaginal delivery at the same calendar year with all subse- quent deliveries performed by vaginal birth only (if multiparous). From the Division of Obstetrics and Gynecology, Department of Clinical Sciences (Drs Leijonhufvud, Andolf, and Altman), Danderyd Hospital, and the Department of Medical Epidemiology and Biostatistics (Drs Leijonhufvud and Altman and Ms Lundholm), Karolinska Institutet, and the Unit of Clinical Epidemiology, Department of Medicine (Drs Granath and Cnattingius), Karolinska University Hospital, Stockholm, Sweden. Received March 18, 2010; revised June 10, 2010; accepted Aug. 17, 2010. Reprints not available from the authors. This study was supported by a grant from the Swedish Society of Medicine and was financed in part by the regional agreement on medical training and clinical research between the Stockholm county council and Karolinska Institutet. 0002-9378/$36.00 © 2011 Published by Mosby, Inc. doi: 10.1016/j.ajog.2010.08.034 Research www. AJOG.org 70.e1 American Journal of Obstetrics & Gynecology JANUARY 2011