The following is a summary of “Influence of pregnancy, parity, and mode of delivery on urinary incontinence and prolapse surgery—a national register study,” published in the January 2023 issue of Obstetrics and Gynecology by Kåverud, et al.

Vaginal birth, parity, and pregnancy’s long-term consequences on the pelvic floor were all debated topics. Surgical registration data may offer a more reliable method for assessing the proportional effect of these risk variables than studies that used self-reported symptoms. For a study, researchers assessed the contribution of vaginal and cesarean delivery, parity, and factors unrelated to childbirth to the long-term risk for reconstructive urogenital surgery using data from three high-quality national registers, namely the Swedish National Quality Register of Gynecological Surgery, the Swedish Medical Birth Register, and the Total Population Register.

In this register-based linkage analysis, women aged ≥ 45 who underwent prolapse or urine incontinence surgery between 2010 and 2017 were included. Nulliparous women, those who had ≥1 cesarean delivery, those who had ≥1 vaginal delivery, and those who had more than one birth were all separated from the surgical cohort. Based on women born in 1960 from the Total Population Register (n=2,309,765), a comparable reference group was created. The prevalence of cesarean and vaginal deliveries among women and their corresponding parity was calculated using the Swedish Medical Birth Register. With 95% CI, the absolute and relative risks were provided per 1,000 women. For dichotomous and continuous variables, Fisher exact tests and the Mann-Whitney U test were used to examine pairwise differences. Using Mantel-Haenszel statistics, the trend between ≥3 ordered categories of dichotomous data was examined.

About 20,488 women got incontinence surgery, while a total of 39,617 women underwent prolapse surgery. 97.8% of women who had prolapse surgery had ≥1 vaginal birth, 0.4% had ≥1 cesarean delivery alone, and 1.9% were nulliparous. For those who underwent incontinence surgery, the corresponding percentages were 93.1%, 2.6%, and 4.3%. Prolapse surgery (relative risk, 1.23; 95% CI, 1.22-1.24; P<.001) and incontinence surgery (related risk, 1.17; 95%CI, 1.15-1.19; P<.001) groups had a disproportionate number of women who gave birth vaginally. In the prolapse surgery (relative risk, 0.14; 95% CI, 0.13-0.15; and relative risk, 0.055; 95% CI, 0.046-0.065; all P<.001) and incontinence surgery (relative risk, 0.31; 95% CI, 0.29-0.33; and relative risk, 0.40; 95% CI, 0.36-0.43) groups, nulliparous and cesarean delivered women were underrepresented. Following a cesarean section, the absolute risk of prolapse surgery was at its lowest (0.09 per 1,000 women; 95% CI, 0.08-0.11) and was 23 times higher (2.11 per 1,000 women; 95% CI, 2.09-2.13) than it was after a vaginal delivery. Following vaginal deliveries, the absolute risk for prolapse and incontinence operations increased steadily with parity. Following a cesarean delivery, the tendency was not seen, which was comparable to nulliparous women. The first vaginal delivery increased the absolute risk of pelvic organ prolapse surgery by six times and that of stress urinary incontinence surgery by ten times (3-fold). The absolute risk for pelvic organ prolapse surgery (∼1/3 of the first vaginal birth) and stress urinary incontinence surgery (∼1/10 of the first vaginal birth) increased the least after the second vaginal birth.

Nearly all surgeries for prolapse and urine incontinence were linked to vaginal parity. After vaginal births, but not after cesarean deliveries, the risk of prolapse surgery increased steadily with parity, but the risk of cesarean deliveries was comparable to that of nulliparous women. Therefore, having a cesarean delivery may shield patients from needing surgery for pelvic organ prolapse and stress urinary incontinence in the future.

Reference: ajog.org/article/S0002-9378(22)00591-9/fulltext