First-Time Mothers Giving Birth Vaginally Have Higher Risk of Later Pelvic Floor Problems

A recent study looked at the incidence of pelvic floor disorders, such as urinary incontinence and pelvic organ prolapse, 1 to 2 decades after women gave birth in order to identify characteristics associated with the problem, which is believed to affect 25% of females in the United States.

The problem is expected to worsen as the US population aged 65 and older doubles between 2010 and 2050. While it is already known that pelvic floor disorders are associated with childbirth, the researchers said they undertook the study because little is known about the course and progression of the issue over time.

After 9 years of annual follow-up, researchers found that women who delivered by cesarean had about half the risk of developing stress urinary incontinence and overactive bladder, compared with women who had a spontaneous vaginal birth. Their risk of pelvic organ prolapse was 70% lower, compared with the same group.

Women who had operative vaginal delivery, where the infant was delivered with the assistance of forceps, vacuum, or other device, were almost twice as likely to experience anal incontinence and pelvic organ prolapse, compared with those who delivered by cesarean.

Of 4072 eligible women, 1528 enrolled between October 2008 and December 2013. Observations continued through April 2017. Participants were categorized as those who had cesarean deliveries only, those who spontaneous vaginal birth (≥1 spontaneous vaginal delivery and no operative vaginal deliveries), or operative vaginal birth (≥1 operative vaginal delivery).

For outcomes, researchers used stress urinary incontinence (SUI), overactive bladder (OAB), and anal incontinence (AI), defined using validated threshold scores from the Epidemiology of Prolapse and Incontinence Questionnaire, and pelvic organ prolapse (POP), measured using the Pelvic Organ Prolapse Quantification Examination.

Among 1528 women (778 in the cesarean birth group, 565 in the spontaneous vaginal birth group, and 185 in the operative vaginal birth group), the median age at first delivery was 30.6 years, 1092 women (72%) had 1 or more births at enrollment (2887 total deliveries), and the median age at enrollment was 38.3 years.

During a median follow-up of 5.1 years (7804 person-visits), there were 138 cases of SUI, 117 cases of OAB, 168 cases of AI, and 153 cases of POP.

For spontaneous vaginal delivery (reference), the 15-year cumulative incidences of pelvic floor disorders after first delivery were as follows: SUI, 34.3% (95% CI, 29.9%-38.6%); OAB, 21.8% (95% CI, 17.8%-25.7%); AI, 30.6% (95% CI, 26.4%-34.9%); and POP, 30% (95% CI, 25.1%-34.9%).

Compared with spontaneous vaginal delivery, cesarean delivery was associated with significantly lower hazard of SUI (adjusted hazard ratio [aHR], 0.46 [95% CI, 0.32-0.67]); OAB (aHR, 0.51 [95% CI, 0.34-0.76]); and POP (aHR, 0.28 [95% CI, 0.19-0.42]); while operative vaginal delivery was associated with significantly higher hazard of AI (aHR, 1.75 [95% CI, 1.14-2.68]) and POP (aHR, 1.88 [95% CI, 1.28-2.78]).

Stratifying by delivery mode, the hazard ratios for POP, relative to a genital hiatus size less than or equal to 2.5 cm, were 3 (95% CI, 1.7-5.3) for a genital hiatus size of 3 cm and 9 (95% CI, 5.5-14.8) for a genital hiatus size greater than or equal to 3.5 cm.

Compared with spontaneous vaginal delivery, cesarean delivery was associated with significantly lower hazard for stress urinary incontinence, overactive bladder, and pelvic organ prolapse, while operative vaginal delivery was associated with significantly higher hazard of anal incontinence and pelvic organ prolapse. A larger genital hiatus was associated with increased risk of pelvic organ prolapse independent of delivery mode.

To the best of the authors’ knowledge, this was the longest cohort study on the epidemiology of pelvic floor disorders to date.

One limitation is that the data for the study were from a single hospital so the results may not be generalized to all populations. Another is that the duration of follow-up was not adequate to look at patterns of hazard in older women. In addition, the sample size was not large enough to further explore some risk factors.

Reference

Blomquist JL, Muñoz A, Carroll M, et al. Association of delivery mode with pelvic floor disorders after childbirth. JAMA. 2018;320(23):2438-2447. doi:10.1001/jama.2018.18315.