Association between multimodal pelvic floor rehabilitation and symptom improvement in postpartum women with low back pain and constipation: a retrospective cohort study

Objective To examine the association between multimodal pelvic floor rehabilitation and improvements in low back pain, functional disability, and constipation-related symptoms among postpartum women with concomitant low back pain and constipation. Methods This single-center retrospective observational cohort study screened 410 postpartum women who underwent rehabilitation assessment between January 2023 and December 2025. Of these, 352 met the baseline eligibility criteria and initiated rehabilitation, including 170 women who initiated conventional active rehabilitation (active comparator) and 182 who initiated multimodal pelvic floor rehabilitation. Treatment initiation was defined as cohort entry, irrespective of subsequent treatment completion or availability of follow-up outcome data. Evaluable follow-up outcomes were available for 300 of 352 treatment initiators (85.2%), with a mean observed baseline-to-follow-up interval of approximately 57.6 days; 52 participants (14.8%) had no evaluable follow-up assessment. Primary baseline-adjusted models incorporated the corresponding baseline outcome, the observed baseline-to-follow-up interval, and clinically selected baseline covariates. Inverse-probability-of-follow-up weighting (IPCW) and a 56-day landmark-anchored delta sensitivity analysis were performed to assess the potential influence of differential follow-up and departures from the missing-at-random assumption. Results In the primary observed-follow-up analysis, multimodal rehabilitation was associated with lower follow-up NRS score (adjusted β = −1.58, 95% CI: −1.79 to −1.37), lower ODI score ( β = −9.71, 95% CI: −10.65 to −8.78), lower PAC-SYM score ( β = −0.62, 95% CI: −0.69 to −0.54), and higher weekly bowel-movement frequency ( β = 1.54, 95% CI: 1.38–1.69); all P < 0.001. IPCW-weighted analyses yielded materially similar estimates, and the associations remained evident under the severe landmark-anchored MNAR sensitivity scenario. Conclusion In this retrospective observational cohort, multimodal pelvic floor rehabilitation was associated with greater improvements in low back pain, functional disability, and constipation-related symptoms than the conventional active rehabilitation comparator. However, the multimodal strategy involved greater treatment exposure, including more supervised treatment sessions and professional contact. Therefore, part of the observed strategy-level association may be attributable to differences in treatment exposure or intensity rather than to the specific multimodal components alone. Given the observational design, these findings should be interpreted as associations rather than evidence of a causal or component-specific treatment effect.