The influence of pregnancy, parity, and mode of delivery on urinary incontinence and prolapse surgery – a national register study
American Journal of Obstetrics and Gynecology
The long-term effects of vaginal delivery, parity, and pregnancy on the pelvic floor remain uncertain and controversial issues. In comparison with studies using self-reported symptoms, surgical register data may offer a more valid mean for evaluating the relative influence of these risk factors. This study used data from three high-quality nationwide registers, the Swedish National Quality Register of Gynecological Surgery, the Swedish Medical Birth Register, and the Total population register,
... o evaluate the contribution of vaginal and cesarean delivery, parity, and factors not related to childbirth on the long-term risk of reconstructive urogenital surgery. This was a register-based linkage study in women aged ≥45 years who underwent urinary incontinence or prolapse surgery 2010-2017. This surgical cohort was divided into nulliparous women, women with ≥1 cesarean deliveries only, ≥1vaginal deliveries, and according to the number of births. A corresponding reference group was constructed based on women born in 1960 from the Total Population Register (n=2,309,765). The Swedish Medical Birth Register was used to determine the rate of women with cesarean and vaginal delivery and their respective parity. Absolute and relative risk (AR, RR) were presented per 1000 women and 95% confidence intervals. Pairwise differences were analyzed with Fisher's exact test and the Mann-Whitney U-test for dichotomous and continuous variables. The trend between ≥3 ordered categories of dichotomous variables was analyzed with Mantel-Haenszel statistics. 39,617 women underwent prolapse surgery and 20,488 incontinence surgery. Among women with prolapse surgery 97.8% had ≥1 vaginal delivery, 0.4%, had ≥1 cesarean delivery only and 1.9% were nullipara. Corresponding figures for those with incontinence surgery were 93.1%, 2.6% and 4.3%. Vaginally delivered women were overrepresented for prolapse surgery (RR 1.23; 95% CI, 1.22-1.24) (both P <0.001) and incontinence surgery (RR 1.17; 95% CI, 1.15-1.19). Nulliparous and cesarean delivered women were underrepresented for prolapse surgery (RR 0.14; 95% CI, 0.13-0.15 and RR 0.055; 95% CI, 0.046-0.065, all P<0.001) and for incontinence surgery (RR 0.31; 95% CI, 0.29-0.33 and RR 0.40; 95% CI, 0.36-0.43). The AR of prolapse surgery was lowest after cesarean delivery [0.09 per 1000 women (95% CI, 0.08-0.11)] and differed by a factor of 23 [AR 2.11 per 1000 women (95% CI 2.09-2.13)] from that after vaginal birth. The AR for prolapse surgery increased consistently with parity after vaginal births. This trend was not observed after cesarean delivery, on par with that in nulliparous women. The first vaginal birth carried the highest increase of AR for POP surgery (x6) and SUI surgery (x3). The second vaginal birth added the lowest AR for POP surgery (∼1/3 of the first vaginal birth) and (∼1/10 of the first vaginal birth) for SUI surgery. Surgery for urinary incontinence and prolapse was almost exclusively related to vaginal parity. The risk for prolapse surgery increased consistently with parity after vaginal births but not after cesarean delivery, while the risk associated with cesarean delivery was on par with that in nulliparous women. Thus, cesarean delivery seems to offer protection from the need for POP and SUI surgery later in life.