Analysis the mediating effect of pelvic floor muscle strength recovery on sexual function and depression in postpartum women

Abstract

BACKGROUND

Postpartum pelvic floor muscle weakness easily triggers sexual dysfunction and depressive mood. The internal interaction mechanism among the three still lacks sufficient empirical verification.

AIM

To investigate the mediating effects of pelvic floor muscle strength recovery on sexual function and depressive symptoms in postpartum women.

METHODS

Postpartum women who underwent standardized rehabilitation at a single center from January 2022 to December 2024 were selected using convenience sampling. Sexual function, depression, and pelvic floor muscle strength recovery were assessed using the Female Sexual Function Index (FSFI), Edinburgh Postnatal Depression Scale (EPDS), and modified Oxford grading scale combined with pelvic floor electrophysiological examination. Pearson’s correlation analysis was used to explore the correlations among variables, and Hayes’ PROCESS Model 4 was used to test the mediating effect of pelvic floor muscle strength recovery.

RESULTS

Among the 130 postpartum women their overall sexual function was moderate with mild depressive symptoms. Regarding pelvic floor muscle strength recovery, 90 (69.23%), 28 (21.54%), and 12 (9.23%) cases were classified as good, moderate, and poor, respectively. There were significant differences in the total FSFI, subscale, total EPDS scores. The incidence of depressive symptoms among postpartum women with different grades of pelvic floor muscle strength recovery (P < 0.05). Correlation analysis showed that total FSFI score was negatively correlated with total EPDS score and positively correlated with pelvic floor muscle strength recovery. Total EPDS score was negatively correlated with pelvic floor muscle strength recovery (P < 0.05). Mediation analysis revealed that pelvic floor muscle strength recovery played a partial mediating role between sexual function and depressive symptoms, with a mediating effect value of -0.153, accounting for 33.60% of total effect (95% confidence interval: -0.252 to -0.053).

CONCLUSION

Sexual function, pelvic floor muscle strength recovery, and depressive symptoms are closely correlated in postpartum women. Pelvic floor muscle strength recovery exerts a partial mediating effect on the process by which sexual function influences depressive symptoms. The assessment and rehabilitation intervention of postpartum pelvic floor function combined with psychological screening is important for promoting the coordinated physical and mental recovery of postpartum women.

Key Words: Postpartum women; Sexual function; Depressive symptoms; Pelvic floor muscle strength; Mediating effect

Core Tip: This study included 130 postpartum women to explore the mediating effect of pelvic floor muscle strength recovery (PFMSR) on sexual function (assessed by Female Sexual Function Index) and depressive symptoms (assessed by Edinburgh Postnatal Depression Scale). The results showed that the PFMSR played a partial mediating role, accounting for 33.60% of the total effect, suggesting the need for clinical attention to the PFMSR and psychological screening for postpartum women’s physical and mental recovery.

INTRODUCTION

Pregnancy and childbirth are special stages in a woman’s life that may cause mechanical and neurological damage to the pelvic floor support structures, leading to decreased pelvic floor muscle strength and pelvic floor dysfunction, further affecting physical and mental health and quality of life. Studies have shown that the incidence of pelvic floor dysfunction is high among postpartum women, among whom decreased pelvic floor muscle strength is common and can induce stress, urinary incontinence, pelvic organ prolapse, and sexual dysfunction[1,2]. Postpartum sexual dysfunction is a common reproductive health problem, mainly manifesting as decreased libido, insufficient sexual arousal, lubrication disorder, and orgasmic disorder, with a high incidence that seriously affects marital relationships and women’s self-identity[3]. At the same time, hormonal fluctuations, role changes, body image changes, and functional disorders all combine to increase the risk of depressive symptoms in postpartum women[4]. Research has previously indicated a link between postpartum sexual dysfunction and depressive symptoms and a close association between the recovery of pelvic floor muscle strength and sexual function, as well as psychological state[2]. However, most existing studies have focused on pairwise relationships, and there are only a limited number of studies on the mediating effect of pelvic floor muscle strength recovery on sexual function and depressive symptoms. The study examined 130 postpartum women to determine whether there was a connection between sexual function and depressive symptoms and how quickly the pelvic floor muscles became stronger after childbirth. The aim was to find out more about the connection between these three factors, provide a scientific basis for creating personalized postpartum rehabilitation programmes that combine “physical rehabilitation and psychological intervention”, and help postpartum women recover physically and mentally.

MATERIALS AND METHODS

Study participants

The Postpartum Rehabilitation Clinic of Hebei Province Children’s Hospital recruited 130 postpartum women who had received standardized rehabilitation treatment from January 2022 to December 2024. Women were selected using convenience sampling.

The inclusion criteria for the study were: Singleton full-term delivery (gestational age ≥ 37 weeks) within the 42-day to 6-month postpartum period; no history of pelvic floor surgery, pelvic tumor, or neurological disease; no severe pregnancy complications (e.g., gestational hypertension, gestational diabetes mellitus) or postpartum complications (e.g., postpartum hemorrhage, infection); spouse alive and regular sexual activity (at least once in the past month); and clear consciousness, able to independently complete questionnaires and examinations.

Voluntary participation in the study and signing of informed consent. The exclusion criteria were: (1) History of mental illness or family history of mental illness; (2) Severe gynecological inflammation, vaginal injury, or other diseases affecting sexual function; (3) Receiving antidepressant medication or psychological treatment; (4) Lost to follow-up or incomplete data during the study period; and (5) History of pelvic floor dysfunction, urinary incontinence, pelvic organ prolapse, or sexual dysfunction before pregnancy.

A total of 130 participants were included in the study. The age of the participants ranged from 22 years to 35 years, with a mean age of 28.62 ± 3.15 years; the gestational age ranged from 37 weeks to 41 weeks, with a mean of 39.25 ± 0.87 weeks. Regarding delivery mode, the majority were vaginal (70.77%) as opposed to C-section (38 cases; 29.23%). The postpartum duration ranged from 42 days to six months, with an average of 3.21 months (± 1.05). In terms of education, 18 (13.85%) had attended junior high school or lower, 42 (32.31%) had attended high school or technical secondary school, and 70 (53.84%) had attended college or higher. The participants’ occupations were as follows: 78 (60.00%) were employed, and 52 (40.00%) were full-time housewives.

Study methods

Data collection: Specialist nurses who had all received the same training during postpartum rehabilitation collected the data. They conducted face-to-face interviews and asked participants to complete a questionnaire. This occurred when the participants were in their first postpartum rehabilitation assessment. Strict confidentiality was maintained throughout the study period. The questionnaires were checked immediately to ensure that all information was complete and accurate, with no missing or incorrect items.

Data collection included the following. The first part of the questionnaire was about general information and was self-designed. These included age, gestational age, delivery mode, postpartum duration, educational level, occupation, and monthly income. The second part was the Female Sexual Function Index (FSFI). The third part was the Edinburgh Postnatal Depression Scale (EPDS). The fourth part assessed the pelvic floor muscle strength recovery.

Assessment tools: (1) FSFI: In the past 4 weeks, the sexual function of 19 items across six domains was assessed: Desire, arousal, lubrication, orgasm, satisfaction, and pain[5]. Items 1, 2, and 13-16 were scored on a scale of 1-5, whereas the others were scored on a scale of 0-5. The scores on this scale range from 0 to 36, with higher scores indicating better sexual function. This scale is reliable and valid, as studies on both general and sexually dysfunctional populations have shown. It has a Cronbach’s α of 0.97 (full sample) and test-retest reliability intraclass correlation coefficient of 0.94. In this study, the Cronbach’s α coefficient for this scale was 0.962; (2) The EPDS is a tool that is often used to assess depressive symptoms in women who have given birth. It has 10 items, each scored from 0 to 3. The total score ranged from 0 to 30[6]. Scoring criteria: A score of 0-9 indicated a good mental state and a low probability of depression. Scores of 10-12 suggest possible depressive symptoms requiring close observation. Scores of ≥ 13 suggest suspected postpartum depression that requires timely intervention. The Cronbach’s α coefficient for this study was 0.895; (3) Evaluation of pelvic floor muscle strength recovery using the modified Oxford grading scale and pelvic floor electrophysiological examination. Modified Oxford grading scale[7]: Vaginal digital examinations were performed by qualified specialists. The strength of the pelvic floor muscles was graded from 0 to 5, with higher scores indicating better contraction efficiency; and (4) Pelvic floor electrophysiological examination[8]: The objective of this study was to quantitatively analyze muscle function using a pelvic floor electrophysiological assessment system. This system measures surface electromyographic signals, fast-/slow-twitch fiber activity, and related dynamic parameters. These parameters reflect the injury and recovery status. In this study, the recovery of pelvic floor muscle strength was evaluated on a scale ranging from excellent to poor, with the categories being excellent, good, moderate, or poor. Excellent: Ideal recovery of contraction efficiency and electrophysiological function; moderate: Partial recovery of pelvic floor muscle function; poor: Unsatisfactory recovery of contraction efficiency and electrophysiological parameters.

Quality control

Standardized training: All nurses received special training before data collection. These included how to administer the scale, pelvic floor muscle assessment protocols, and interview strategies. This was done to ensure that everything was performed similarly. Strict screening: We selected participants according to predefined inclusion and exclusion criteria to minimize confounding effects. Questionnaire quality control: Specialist staff cross-checked the questionnaires after they were collected, supplementing missing items and excluding unqualified samples in a timely manner. The fourth point concerns professional assessments. Two senior postpartum rehabilitation physicians independently assessed the pelvic floor muscle function and resolved any disagreements by consensus. Data management: The database was constructed using parallel double entries, followed by consistency verification to reduce entry bias.

Statistical analysis

Basic statistical analyses were performed using SPSS 26.0, with the Hayes PROCESS macro (v3.5) used for complex model testing. Continuous variables were described as mean ± SD. Between-group differences were analyzed using an independent-sample t-test or one-way analysis of variance. Categorical variables are presented as n (%), and between-group comparisons were performed using the χ² test. Pearson’s correlation analysis was used to quantify the relationships among sexual function, depressive symptoms, and pelvic floor muscle strength recovery. The mediating effect was tested using Model 4 of the PROCESS macro. The bootstrap resampling technique (5000 iterations) was applied to calculate 95% confidence intervals. The presence of a statistically significant mediating effect was indicated by the 95% confidence interval not including zero. Statistical significance was set at P < 0.05. significant. To reduce potential confounding bias, multivariate linear regression analyses were performed after adjusting for delivery mode, parity, postpartum duration, breastfeeding status, and body mass index. These variables were included as covariates in the mediation analysis.

RESULTS

General distribution of study subjects

The age of the 130 postpartum women ranged from 22 years to 35 years. Of these, 28 (21.54%) were aged 22-25 years, 50 (50.00%) were aged 26-30 years, and 37 (28.46%) were aged 31-35 years. Doctors delivered the babies vaginally (92 cases, 70.77%) or via caesarean section (38 cases, 29.23%). The duration of the postpartum period ranged from 42 days to 3 months (78 patients, 60.00%) and from 3 months to 6 months (52 patients, 40.00%). Educational level included college degree or above (70 cases, 53.84%), high school/technical secondary school (42 cases, 32.31%), and junior high school or below (18 cases, 13.85%). Employment status included working (78 cases, 60.00%) and full-time housewives (52 cases, 40.00%).

The study focused on the overall status of sexual function, depressive symptoms, and the recovery of pelvic floor muscle strength

The total FSFI score in 130 postpartum women was (24.35 ± 5.12), with the following dimensions: Libido (3.25 ± 0.87), arousal (4.12 ± 1.05), lubrication (4.36 ± 1.12), orgasm (3.89 ± 1.01), satisfaction (4.52 ± 1.08), and pain (4.21 ± 1.03). The total EPDS score was (8.76 ± 3.25), with 98 cases (75.38%) showing no depressive symptoms (EPDS ≤ 9), 22 cases (16.92%) indicating possible depressive mood (10 ≤ EPDS ≤ 12), and 10 cases (7.69%) suggesting possible postpartum depression (EPDS ≥ 13). Pelvic floor muscle strength recovery was classified as excellent in 90 patients (69.23%), moderate in 28 patients (21.54%), and poor in 12 patients (9.23%).

Comparison of total FSFI scores among postpartum women with different pelvic floor muscle strength recovery grades

There were significant differences in the total FSFI scores among postpartum women with different pelvic floor muscle strength recovery grades (P < 0.05). Post hoc tests revealed that the excellent group had significantly higher total FSFI scores than the moderate and poor groups, whereas the moderate group had significantly higher scores than the poor group (all P < 0.05) (Table 1).

Table 1 Comparison of total Female Sexual Function Index scores among postpartum women with different pelvic floor muscle strength recovery grades (mean ± SD, point).

Pelvic floor muscle strength recovery grade	Case (n)	II	F	P value	Post-hoc test (P value)
Excellent-good group	90	27.89 ± 3.25	49.546	< 0.001	Excellent-good vs moderate: < 0.001; Excellent-good vs poor: < 0.001; moderate vs poor: 0.001
Moderate group	28	23.15 ± 4.02
Poor group	12	18.62 ± 3.87

FSFI: Female Sexual Function Index.

Comparison of FSFI dimensions in postpartum women with different pelvic floor muscle strength recovery grades

There were significant differences in the scores for all dimensions of the FSFI among postpartum women with different pelvic floor muscle strength recovery grades (all P < 0.05). The excellent group scored the highest in six dimensions: Libido, sexual arousal, lubrication, orgasm, satisfaction, and pain, followed by the moderate group, while the poor group had the lowest scores. All pairwise comparisons between the groups were statistically significant (all P < 0.05) (Table 2).

Table 2 Comparison of Female Sexual Function Index dimension scores in postpartum women with different pelvic floor muscle recovery grades (mean ± SD, point).

Pelvic floor muscle strength recovery grade	Case (n)	Sexuality	Sexual arousal	Lubricating	Orgasm	Degree of satisfaction	Pain
Excellent-good group	90	3.68 ± 0.72	4.65 ± 0.92	4.89 ± 0.98	4.32 ± 0.95	4.95 ± 0.92	4.68 ± 0.95
Moderate group	28	3.12 ± 0.85	4.01 ± 1.02	4.25 ± 1.05	3.85 ± 1.01	4.42 ± 1.03	4.15 ± 1.02
Poor group	12	2.45 ± 0.78	3.21 ± 0.95	3.32 ± 1.01	3.02 ± 0.98	3.68 ± 1.05	3.35 ± 0.98
F value		17.388	15.026	15.391	10.799	11.081	11.632
P value		< 0.001	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001

Comparison of EPDS scores among women with different pelvic floor muscle strength recovery grades after childbirth

There were significant differences in the total EPDS scores among postpartum women with different pelvic floor muscle strength recovery grades (P < 0.05). Post hoc tests revealed that the excellent group had significantly lower total EPDS scores than the moderate and poor groups, whereas the moderate group had significantly lower scores than the poor group (all P < 0.05; Table 3).

Table 3 Comparison of total Edinburgh Postnatal Depression Scale scores among postpartum women with different pelvic floor muscle recovery grades (mean ± SD, point).

Pelvic floor muscle strength recovery grade	Case (n)	FSFI	F value	P value	Post-hoc test (P value)
Excellent-good group	90	7.25 ± 2.85	27.839	< 0.001	Excellent group vs moderate group: < 0.001; excellent group vs poor group: < 0.001; moderate group vs poor group: < 0.001
Moderate group	28	9.86 ± 3.12
Poor group	12	13.52 ± 3.56

FSFI: Female Sexual Function Index.

Comparative study on the incidence of postpartum depression in women with different recovery grades of pelvic floor muscle strength

There were significant differences in the incidence of postpartum depressive symptoms among women with different levels of pelvic floor muscle strength recovery levels (P < 0.05). The excellent group (90 cases) had the highest incidence of no depressive symptoms (90.00%) and the lowest incidence of possible postpartum depression (1.11%). The moderate group (28 cases) had an incidence of no depressive symptoms (57.14%) and an incidence of possible postpartum depression (7.14%). The poor group (12 cases) had the lowest incidence of no depressive symptoms (25.00%) and the highest incidence of possible postpartum depression (41.67%) (Table 4).

Table 4 Comparison of postpartum depression symptom incidence among women with different pelvic floor muscle strength recovery grades, n (%).

Pelvic floor muscle strength recovery grade	Case (n)	No depressive symptoms	Depressive mood	Postpartum depression	χ2	P value
Excellent-good group	90	81 (90.00)	8 (8.89)	1 (1.11)	47.172	< 0.001
Moderate group	28	16 (57.14)	10 (35.71)	2 (7.14)
Poor group	12	3 (25.00)	4 (33.33)	5 (41.67)

Correlation analysis of postpartum FSF1 and EPDS scores with pelvic floor muscle strength recovery

The total FSFI score in postpartum women negatively correlated with the total EPDS score and positively correlated with the degree of pelvic floor muscle strength recovery (after quantification; P < 0.05). The total EPDS score was negatively correlated with the degree of pelvic floor muscle strength recovery (after quantification; P < 0.05; Table 5).

Table 5 Correlation analysis of total Female Sexual Function Index and Edinburgh Postnatal Depression Scale scores and pelvic floor muscle strength recovery in postpartum women.

Correlation/indicators	Case (n)	mean ± SD	Pearson (r)	t	P value
FSFI total score and EPDS total score	130	FSFI: 24.35 ± 5.12; EPDS: 8.76 ± 3.25	-0.603	8.546	< 0.001
FSFI total score and pelvic floor muscle strength recovery degree	130	Pelvic floor muscle strength rating: 2.60 ± 0.58 (excellent = 3, moderate = 2, poor = 1)	0.687	10.702	< 0.001
The correlation between EPDS total score and pelvic floor muscle strength recovery	130	Pelvic floor muscle strength rating: 2.60 ± 0.58 (excellent = 3, moderate = 2, poor = 1)	-0.570	7.856	< 0.001

FSFI: Female Sexual Function Index; EPDS: Edinburgh Postnatal Depression Scale.

Results of the mediation effect test of the recovery degree of pelvic floor muscle strength

Using the total FSFI score of postpartum women as the independent variable (X), the total EPDS score as the dependent variable (Y), and the degree of recovery of pelvic floor muscle strength (rated excellent = 3, moderate = 2, poor = 1) as the mediating variable (M), the Hayes PROCESS macro program model 4 was employed to test the mediating effect. The results are shown in the table below: The recovery degree of pelvic floor muscle strength partially mediates the relationship between postpartum women’s sexual function and depressive symptoms. The total effect size was -0.454 (P < 0.05), with a direct effect size of -0.301 and a mediating effect size of -0.153 (accounting for 33.60% of the total effect). The 95% confidence interval for the mediating effect was -0.252 to -0.053, excluding 0, indicating the validity of the mediating effect (Table 6).

Table 6 Results of the mediation effect test for the recovery degree of pelvic floor muscle strength.

Effect type	Coefficient	SE	t	P value	95% confidence interval	Effect proportion (%)
The direct effect of the independent variable (X) on the dependent variable (Y)	-0.301	0.071	4.267	< 0.001	-0.440 to -0.163	-
The effect of independent variable (X) on mediator variable (M), and the effect of mediator variable (M) on dependent variable (Y)	0.098	0.009	10.696	< 0.001	0.080-0.116	-
The effect of independent variable (X) on mediator variable (M), and the effect of mediator variable (M) on dependent variable (Y)	-1.553	0.494	-3.143	0.002	-2.522 to -0.585	-
Mediation effect (X → M → Y)	-0.153	0.051	-3.016	0.003	-0.252 to -0.053	33.603
Gross effect (X → Y)	-0.454	0.053	-8.552	< 0.001	-0.558 to -0.350	100.00

DISCUSSION

Impairment of postpartum pelvic floor function, sexual dysfunction, and postpartum mood disorders are three common problems that threaten the physical and mental health of parturient women; however, their interactive pathways have not been fully clarified. In the current clinical practice, postpartum rehabilitation interventions often present a situation in which physical treatment and psychological support are separate, lacking integrated and collaborative intervention strategies. The present study found that sexual function scores were significantly negatively correlated with depression scale scores in postpartum women, whereas the recovery level of pelvic floor muscle tone was positively associated with sexual function indicators and inversely associated with depression severity. Mediation analysis further revealed that the recovery of pelvic floor muscle function exerted a partial mediating effect between sexual function and depressive symptoms, with a mediating effect of 33.60%. These findings suggest that physical rehabilitation, sexual health quality, and emotional regulation in parturient women constitute an interconnected dynamic system rather than isolated health dimensions, and that pelvic floor function rehabilitation may serve as a key hub linking physical recovery and psychological adjustment.

The FSFI score of the subjects in this group was 24.35 ± 5.12, generally at a relatively low level; the EPDS score was 8.76 ± 3.25. Although most participants did not reach the clinical depression threshold, some individuals exhibited varying degrees of negative emotions. These results are consistent with the physical and psychological characteristics of the special period from 42 days to six months postpartum. This stage involves structural repair of the pelvic floor and maternal role adaptation[9]. Multiple stressors, including birth canal injury, fluctuations in estrogen and progesterone levels, neuroendocrine changes caused by lactation, superimposed sleep deprivation, and increased parenting burden, can all exert negative effects on sexual health and mood status[10,11]. Therefore, the coexistence of postpartum sexual dysfunction and emotional distress is inevitable. It is worth emphasizing that sexual function assessment depends not only on the degree of anatomical recovery but also on multi-dimensional factors such as body image satisfaction, spouse interaction patterns, physical comfort, and psychological adjustment ability; therefore, it can be used as a sensitive indicator reflecting the overall rehabilitation status of parturient women[12].

The results of this study showed that the degree of pelvic floor muscle strength recovery in postpartum women was positively correlated with the total FSFI and subscale scores. Specifically, better recovery of pelvic floor muscle function was associated with better sexual desire, arousal efficiency, vaginal lubrication, orgasm experience, sexual satisfaction, and pain relief. This finding is consistent with the physiological functions of the pelvic floor muscle group. From a mechanistic perspective, the pelvic floor muscle group plays a key role in supporting the pelvic organs, maintaining vaginal tightness, and regulating sexual responses. Good muscle strength and coordinated contraction help maintain local tissue tension and promote blood circulation and neural sensitivity in the pelvic region, thereby optimizing the sexual experience[13,14]. Conversely, poor postpartum pelvic floor function rehabilitation predisposes parturient women to vaginal laxity, dyspareunia, and even sexual avoidance due to the fear of stress and urinary incontinence, ultimately leading to decreased sexual quality[15,16]. Additionally, this study observed that the pain subscale scores improved with an increase in muscle strength recovery, indicating that pelvic floor rehabilitation not only affects the acquisition of sexual pleasure but also reduces discomfort during intercourse. These two factors jointly determined the overall recovery of sexual function[17].

At the psychological level, the results of this study showed that poorer pelvic floor muscle strength recovery was associated with higher EPDS scores and a higher incidence of depressive symptoms, especially in the poor recovery group in which the proportion of suspected postpartum depression was higher. Our results indicate that the impact of pelvic floor dysfunction is not limited to the local physical level but may also extend to psychological status through multiple pathways[18]. In postpartum women, physical recovery is often directly related to self-evaluation and confidence in life. Once problems such as urinary leakage, perineal distension, and decreased sexual quality occur, parturient women are prone to negative experiences such as embarrassment, shame, and self-blame and may thus worry about the impact on marital relationships[19,20]. If such adverse experiences persist, they may gradually accumulate and further aggravate the emotional burden[21]. From this perspective, poor pelvic floor muscle recovery results in a continuous process, starting from physical discomfort and gradually affecting cognitive evaluation and emotional responses[22].

Postpartum pelvic floor dysfunction may influence depressive symptoms not only through physical discomfort, but also through complex neurobiological and psychosocial pathways. From a neurobiological perspective, the pelvic floor muscles are closely connected to the autonomic nervous system and central emotional regulation circuits. Abnormal pelvic floor muscle tension and impaired neuromuscular coordination may alter somatosensory afferent inputs from the pelvic region, thereby influencing limbic system activity and emotional regulation. Additionally, chronic pelvic discomfort, dyspareunia, and impaired sexual responses may continuously activate stress-related neuroendocrine pathways, thereby contributing to negative emotional states.

From a biopsychosocial perspective, postpartum women often experience substantial changes in their body image, self-identity, and marital intimacy. Pelvic floor and sexual dysfunctions may increase feelings of embarrassment, reduced femininity, loss of body confidence, and concerns about partner relationships. These negative self-perceptions may gradually impair self-esteem and emotional resilience, thereby increasing vulnerability to depressive symptoms. Therefore, the association between pelvic floor muscle recovery, sexual function, and depressive symptoms should be understood as a multidimensional interaction involving physiological recovery, psychological adaptation, and social relationship reconstruction rather than as an isolated clinical phenomenon.

This study further revealed that the level of pelvic floor muscle strength recovery plays a partial mediating role in the relationship between postpartum sexual function and depressive symptoms. This finding indicates that the effect of sexual function on depression is not only exerted through direct pathways, and part of the effect is achieved through the physiological mechanism of pelvic floor function reconstruction. Specifically, better sexual performance usually reflects ideal pelvic floor rehabilitation, and good recovery of pelvic floor function can further exert an antidepressant effect by improving sexual experience, enhancing physical control, and reducing the psychological burden caused by dysfunction[23,24]. However, given that only a partial mediating effect was observed in this study, the association between sexual function and depressive symptoms may also be regulated by multiple factors such as marital quality, social support system, sleep quality, endocrine fluctuations, delivery trauma, and infant care pressure[25,26]. Therefore, the interpretation of mental health problems in postpartum women needs to overcome the limitations of a single biomedical or psychological perspective and should be systematically analyzed using a bio-psychosocial integrated model.

This study has several limitations. First, this was a single-center cross-sectional study with a relatively small sample size, and convenience sampling was used. Therefore, the representativeness of the sample was limited and the findings may not be generalizable to postpartum women who did not receive standardized rehabilitation interventions, women from primary healthcare institutions, or those living in remote areas. Second, due to the cross-sectional design, causal and temporal relationships between sexual function, pelvic floor muscle strength recovery, and depressive symptoms could not be established. Although a mediation analysis was performed, the results only reflected statistical associations rather than definite causal pathways. Longitudinal prospective studies are required to further verify the temporal sequences and causal mechanisms of these variables. Third, this study did not include baseline pre-pregnancy information regarding pelvic floor function, sexual function, or psychological status, which limited the ability to control for individual baseline differences. In addition, several important confounding and moderating variables, including marital quality, social support, sleep quality, parenting stress, breastfeeding status, parity, delivery mode, postpartum duration, and body mass index, were not fully adjusted for in the current mediation model. These factors have been reported to significantly influenced the postpartum sexual function and depressive symptoms in previous studies. Fourth, although participants with a history of psychiatric disorders were excluded, the exclusion criteria did not explicitly exclude women with preexisting pelvic floor or sexual dysfunction before pregnancy, which may have introduced a residual confounding bias. Future studies should conduct multicenter, large-sample, prospective cohort investigations and incorporate additional psychosocial and obstetric variables to construct moderated mediation or longitudinal structural equation models. Such approaches may help to clarify the differential association pathways among different postpartum populations.

CONCLUSION

In summary, sexual function, pelvic floor muscle strength recovery, and depressive symptoms are closely correlated in postpartum women. Pelvic floor muscle strength recovery exerts a partial mediating effect on the processes by which sexual function influences depressive symptoms. In clinical practice, attention should be paid to the role of pelvic floor rehabilitation in overall postpartum recovery. Early identification, timely intervention, and comprehensive support can effectively improve the physical and mental health of postpartum women.