Clinical Context

Pelvic floor disorders, such as stress urinary incontinence (SUI), overactive bladder (OAB), and pelvic organ prolapse (POP), are associated with childbirth and have a prevalence of approximately 25% among US women. However, the course and progression of pelvic floor disorders over time has not been thoroughly studied, and the biological mechanisms underlying pelvic floor disorders are still unclear. The aging of the US population will further increase the healthcare burden and costs of pelvic floor disorders, as prevalence is more than doubled among women older than 80 years.

The goals of this longitudinal cohort study were to assess the incidence of pelvic floor disorders after childbirth and to identify maternal and obstetrical factors associated with patterns of incidence 10 to 20 years after delivery.

Study Synopsis and Perspective

The risk for pelvic floor disorders after childbirth, ranging from urinary incontinence to POP, are significantly lower with cesarean delivery compared with spontaneous vaginal delivery, whereas operative vaginal delivery, such as the use of forceps, conveys the highest risk for the disorders, according to a study of more than 1500 women up to almost 2 decades after childbirth.

"Results of this study showed a substantial difference in pelvic floor disorder incidence based on a woman's obstetrical characteristics," Joan L. Blomquist, MD, from the Department of Gynecology, Greater Baltimore Medical Center, Maryland, and colleagues write in their article, published in JAMA.

"The cumulative incidence of each pelvic floor disorder was significantly associated with delivery mode," they add.

Studies have shown as many as 25% of women in the United States have at least 1 pelvic floor disorder, and the rate is more than twice as high for women older than 80 years, but although childbirth is a known key risk factor, research is lacking on long-term risks and the association with specific obstetrical procedures.

"Data from the present study build on those observations by providing a more complete picture of incidence over time," Dr Blomquist and colleagues note.

In an interview with Medscape Medical News, however, Dr Blomquist would not be drawn on how this research should inform individual choices about birth delivery methods.

She noted that a multitude of considerations go into decisions about birth delivery mode, and that this study is not designed to suggest recommendations for any 1 method over another.

"This is just 1 piece in the very large puzzle that a provider and patient need to consider when determining the best delivery mode for that patient," she said.

"The study does not give information about who is the best candidate for which delivery type. However, it does tell us that if someone had an operative vaginal delivery, they are at higher risk of developing these disorders in the future.

"As a result, there may be a role for secondary prevention, such as avoidance of obesity or certain exercises, in these high-risk populations."

Women Followed-up for 18 Years After Giving Birth

For the study, Dr Blomquist and colleagues evaluated data on 1528 women in the longitudinal Mother's Outcome After Delivery study who enrolled from October 2008 to December 2013.

The women, who were enrolled 5 to 10 years after their first delivery, were followed-up annually for up to 9 years. The longest time after first delivery when a participant was seen in the study was 18.7 years.

Participants had a median age of 30.6 years at first delivery, and among them, 778 delivered by cesarean birth, 565 by spontaneous vaginal birth, and 185 by operative vaginal birth, including vacuum assistance (ventouse) or the use of forceps.

Most (72%) were multiparous at enrolment, and among those women, the median age at enrolment was 38.3 years. Outcomes were assessed annually via the Epidemiology of Prolapse and Incontinence Questionnaire and a physical examination (gynecologic, height, and weight information).

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

For those in the reference group of spontaneous vaginal delivery, the 15-year incidence of pelvic floor disorders after the first childbirth was 34.3% for SUI, 21.8% for OAB, 30.6% for AI, and 30.0% for POP.

Comparatively, those in the cesarean delivery group had significantly lower incidence of SUI (adjusted hazard ratio [aHR], 0.46) and OAB (aHR, 0.51), and a much lower risk for POP (aHR, 0.28).

Women who had operative vaginal delivery, meanwhile, had a significantly higher hazard of AI (aHR, 1.75) and POP (aHR, 1.88) compared with the reference group of spontaneous vaginal delivery.

Genital Hiatus Size Also Plays a Role

The researchers also found that genital hiatus size, representing the distance between the external urethral meatus and the posterior midline hymen, was associated with the risk for POP. An enlarged genital hiatus is also referred to by some providers as a "relaxed vaginal outlet."

Among women with the same mode of delivery, including women in the cesarean birth group, there was a statistically and clinically significant association between genital hiatus size and pelvic floor disorder.

Compared with a size of 2.5 cm or less, the adjusted hazard risk for POP was significantly higher with genital hiatus size of 3 cm (aHR, 3.0), and even greater with a size of 3.5 cm or higher (aHR, 9.0).

These findings suggest genital hiatus could be a useful predictor. "[G]enital hiatus size is viable as a marker to monitor the risk of POP over time," the authors suggest. "Indeed, the changes in genital hiatus may actually be a mechanism for the development of POP, regardless of delivery mode."

Pelvic Floor Disorders Develop at Different Times; Different Causes

The longitudinal nature of the study adds to prior research by showing the incidence of pelvic floor disorders in relation to the duration of time since childbirth, Dr Blomquist explained to Medscape Medical News.

"This study allows us to see patterns of incidence of the various pelvic floor disorders over the first 2 decades after childbirth," she said.

"In addition to finding that the delivery mode is associated with the incidence of pelvic floor disorders, we also noted different [latency] patterns between the different pelvic floor disorders."

For example, the findings indicate that the peak incidence of stress incontinence is within the first 5 years after childbirth, whereas POP has a longer latency, with the peak incidence more than 20 years after childbirth, Dr Blomquist explained.

This indicates that there are likely different causes of the various pelvic floor disorders, the authors conclude.

The study received support from the grants R01HD082070 and R01HD056275 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Dr Blomquist had no disclosures to report.

JAMA. 2018;320(23):2438-2447.

Clinical Implications

• In a longitudinal cohort study, risk for pelvic floor disorders after childbirth varied by delivery mode, and risk for POP was increased with a larger genital hiatus, independent of delivery mode.
• Having a history of operative vaginal delivery warns of higher future risk of developing pelvic floor disorders and may suggest a role for secondary prevention, such as maintaining healthy body weight and performing certain exercises.
• Implications for the Healthcare Team: Various considerations affect decisions about birth delivery mode, and the study was not designed to recommend any specific mode over another, nor to affect patient selection for a specific delivery type.
• The role of the healthcare team member is to continue to enhance their own knowledge through seeking up to date evidence, guide and support patients to improve outcomes, in collaboration with other members of the healthcare team. 

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