How do obstetric, neurologic and gastrointestinal risk factors compare with sexual practices as predictors of fecal incontinence in existing studies?

1. Obstetric injury: clear mechanistic link, mixed epidemiologic weight

Obstetric anal sphincter injuries (OASIS) create a plausible causal pathway to FI because vaginal delivery can directly tear the sphincter or injure pudendal nerves, and specialty and obstetric reviews list operative vaginal delivery and sphincter laceration as key postpartum risk factors ^{[1] [5] [6]}; however, large community-based analyses and national surveys show that after adjustment for age and bowel symptoms the number of vaginal births or obstetric events often do not remain significant independent predictors of late‑onset FI, indicating that obstetric trauma increases short‑term risk but may play a diminished role decades later compared with other factors ^{[7] [2]}.

2. Gastrointestinal (stool/bowel) factors: the dominant, modifiable predictors

Across population studies and case‑control analyses, bowel disturbances—particularly chronic diarrhea and rectal urgency associated with IBS—emerge as the strongest independent predictors of FI, sometimes with very large effect sizes, and are repeatedly recommended as primary targets for prevention and initial management before imaging or surgical referral ^{[2] [3] [8]}; systematic reviews and epidemiologic syntheses therefore emphasize the quantity and consistency of stool and rectal sensorimotor dysfunction as central mechanisms driving community FI prevalence ^{[9] [10]}.

3. Neurologic and systemic contributors: important but less common in populations

Neurologic disorders that impair pelvic sensation or sphincter control—spinal cord injury, multiple sclerosis, diabetes, stroke—are well‑documented causes of anorectal sensorimotor dysfunction and are cited across reviews as risk factors for FI, and institutional cohorts frequently note neurologic disease and cognitive/functional decline as predictors in older or hospitalized populations ^{[8] [2] [11]}; nonetheless, because these conditions are less prevalent than bowel disturbances, they often do not account for most FI cases in community surveys despite strong mechanistic plausibility ^[2].

4. Sexual practices (anal penetrative intercourse): limited, low‑quality evidence

Evidence linking API to FI is sparse: a single institutional cross‑sectional survey reports that a substantial minority of women have tried API and that pelvic floor symptoms, including anal incontinence, were reported in that cohort, but the design is cross‑sectional, based on self‑report, and cannot establish temporality or control fully for confounders such as diarrhea, parity, or prior sphincter injury ^[4]; major epidemiologic reviews and population studies do not list sexual practice as a leading independent predictor, reflecting the limited scale and generalizability of the API literature compared with extensive data on obstetric, GI and neurologic factors ^{[2] [9]}.

5. Comparative strength, confounding and where biases lie

When risk factors are compared in multivariable models, bowel disturbances and age/co‑morbidities consistently dominate as independent predictors, obstetric sphincter trauma retains importance particularly for early postpartum FI or clinic populations but often loses independent significance in late‑onset, population‑level analyses, and neurologic disease confers high individual risk but accounts for fewer total cases; sexual practices have the weakest evidence base and are vulnerable to reporting bias and confounding, meaning current data cannot support API as a population‑level independent predictor on par with GI, obstetric or neurologic causes ^{[3] [7] [2] [4]}.

6. Bottom line and implications for clinicians and researchers

The literature converges on a hierarchy: bowel disturbances and modifiable stool factors are the dominant, actionable predictors of FI in community settings, obstetric sphincter injury is an important mechanistic and clinical contributor—especially in younger or postpartum women—and neurologic disease is a potent but less frequent cause; sexual practices such as API remain poorly studied and cannot presently be ranked alongside established predictors without larger, longitudinal, controlled research that accounts for bowel habit, obstetric history and neurologic status ^{[2] [3] [5] [4]}.