Review Reports - Exploring the Link Between Vaginal Delivery and Postpartum Dyspareunia: An Observational Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study is based on determining a correlation between vaginal delivery and dysparunia. The study is stated as prospective but some details of vaginal birth were missing in 232 questionnaires.

Abstract: There are several grammatical errors in the abstract. Key words should not be enumerated.

Introduction. An extensive review of the aetiology of dysparunia and chronic pelvic pain has been covered. This forms the basis of our understanding of dysparunia. The categorization of the latter into superficial and deep is relevant. However, there is no reference made to this two subgroups in the study.

The whole introduction seems to focus on both dysparunia and chronic pelvic pain. This could be shortened. More reviews about the correlation between vaginal delivery and dysparunia are warranted. The study has focussed on one year after birth. We need more details about the reason for this.

The study design is based on data based between 1991-2006. These are very old data. Kindly justify the value of such studies. More recent data would be applicable our understaning.

The variables to be studies should be itemized for clarify. What are the inclusion and exclusion criteria? Were patients who have premorbid psychological conditions or those who developed anxiety and depression after delivery excluded?

Could we have more details of the questionnaire? Were they validated? How were the subjects recruited for trhe study. Were the self-answered, if so how long did it take to complete the questionnaire? Since the study is to determine dysparunia, more details are required. Only one question pertaining to dysparunia has been included i.e. yes or no. Since the problem of dyspaunia is much wider, such an approach would test the validity of the results.

Kindly provide details of when the questionnaires were sent to subjects (time period). Explain the validation process of the questionnaires used in the study.

LIne 124: Please state what two decades refer to. References are required for Lines 135-136.

Table 1: Foot notes to explain the abbreviations.

Results.

The weight of the newborn and prolonged labour ( which may have warranted oxytocin augmentation) are useful variables to reflect on model of delivery and perineal injuries.

Discussion.

The discussion is rather broad , touching on a range of topics. The relationship between perineal injuries and oxytocin use in 2nd stage is apparent. They may be related to each other. Could this also be included in the discussion.

Reference: They are comprehensive. Kindly format them.

Lines 144-164: Please write this in one paragraph.

Comments on the Quality of English Language

The abstract requires improvement.

Paragraphing is not well done; some are written as single sentences.

Author Response

Comments 1: The study is based on determining a correlation between vaginal delivery and dyspareunia. The study is stated as prospective, but some details of vaginal birth were missing in 232 questionnaires.

Response 1: Thank you for pointing this out. In line 111 we mentioned that the data originate from a prospective database (obstetric registry of a Swiss teaching hospital, see Response 7). This study with the focus on dyspareunia itself is retrospective. As the mentioned wording seems to lead to misunderstanding the text was changed to:

Line 119 (clean version) / 149 (track change version)

The data originate from an obstetric registry from 1991-2006 in the Department of Obstetrics and Gynecology of a Swiss teaching hospital.

In 232 questionnaires there were no information about the type of perineal tear. As perineal tear was analyzed as a potential influencing factors, these questionnaires weren’t included to not falsify the result. We considered the assumption that it could be an intact perineum to be incorrect.

Comments 2: Abstract: There are several grammatical errors in the abstract. Key words should not be enumerated.

Response 2: Agree. We have, accordingly, revised text for errors and deleted the numbers after the key words. The corrected abstract is now this:

Abstract

Background/Objective: Dyspareunia negatively affects women’s life. Up to 35% suffer from postpartum dyspareunia. Many factors may influence the occurrence of postpartum dyspareunia, but little is known about them. The study aimed to look at the frequency of dyspareunia one year postpartum in a cohort of primiparae. Which perinatal factors influence the frequency of postpartum dyspareunia? Methods: A total of 3264 primiparae were included in this observational cohort-study. Perinatal factors were documented, and one year postpartum, a specially designed questionnaire was sent to them. The primary outcome was the frequency of dyspareunia one year postpartum. The secondary outcomes included potential influencing factors such as birthing method (spontaneous bed delivery, spontaneous delivery other than bed, water delivery, and vacuum assisted delivery); perineal injuries (first- and second-degree perineal tears, obstetric anal sphincter injuries (OASIS), and episiotomies); and the use of oxytocin. Results: Postpartum dyspareunia was observed in 15% of the 3264 primiparae. In multivariate analysis, there were influences found in the perineal injury group, especially for first- and second-degree perineal tears and OASIS. In the oxytocin group, a trend toward a higher rate of postpartum dyspareunia was observed. No influence of the different birthing methods was found. Conclusion: Postpartum dyspareunia, affecting 15% of women one year after vaginal delivery, is associated with perineal injuries, particularly minor perineal tears and OASIS. This highlights the importance of good preparation of the perineum and pelvic floor before delivery, efficient perineal protection during labor, and the use of a precise repair technique for all perineal injuries.

Keywords: dyspareunia; delivery; perineal injury; OASIS; oxytocin; birthing method

Comments 3: Introduction. An extensive review of the aetiology of dysparunia and chronic pelvic pain has been covered. This forms the basis of our understanding of dysparunia. The categorization of the latter into superficial and deep is relevant. However, there is no reference made to this two subgroups in the study.

Response 3: Thank you for pointing this out. The categorization deep and superficial is mentioned in line 44-45 (clean version) / 46 – 47 (track-change version).

We added literature indicating that deep dyspareunia is particularly associated with endometriosis; it is less expected around birth but may become an issue after a C-section or during breastfeeding.

New literature:

Wahl KJ, Orr NL, Lisonek M, Noga H, Bedaiwy MA, Williams C, Allaire C, Albert AY, Smith KB, Cox S, Yong PJ. Deep Dyspareunia, Superficial Dyspareunia, and Infertility Concerns Among Women With Endometriosis: A Cross-Sectional Study. Sex Med. 2020 Jun;8(2):274-281. doi: 10.1016/j.esxm.2020.01.002. Epub 2020 Feb 13. PMID: 32061579; PMCID: PMC7261667.

The questionnaire didn’t differentiate between these superficial and deep dyspareunia. This point is now added in the outcome measures and the limitations of the study.

Line 213 (clean version) / 261 (track change version)

No further subclassification of superficial and deep dyspareunia was performed.

Line 432 (clean version) / 523 (track change version)

Postpartum Dyspareunia was not subclassified into deep and superficial forms.

Comments 4: The whole introduction seems to focus on both dyspareunia and chronic pelvic pain. This could be shortened. More reviews about the correlation between vaginal delivery and dyspareunia are warranted. The study has focused on one year after birth. We need more details about the reason for this.

Response 4: Thank you for your remarks. The introduction was changed as following, additional text is highlighted:

Line 41 (clean version) / 43 (track change version)

1. Introduction

Dyspareunia is classified as a subtype of chronic pelvic pain and is defined as the complaint of persistent or recurrent pain or discomfort associated with attempted or complete vaginal penetration. [1] It may be further differentiated into superficial dyspareunia, typically localized to the vulva or vaginal introitus, and deep dyspareunia, which is experienced during deeper penetration and frequently associated with pelvic pathology.

Chronic pelvic pain is characterized by pain persisting for a minimum duration of six months. Together with dysmenorrhea and noncyclical pelvic pain, dyspareunia constitutes a core component of the chronic pelvic pain syndrome. [2] Chronic pelvic pain syndrome is associated not only with physical morbidity but also with negative cognitive, behavioral, sexual and emotional consequences, as well as with symptoms and signs related to lower urinary tract, sexual, bowel, pelvic floor or gynecological dysfunction.

The etiology of dyspareunia is heterogeneous, necessitating a comprehensive and differentiated diagnostic approach. [3] In gynecological practice, infectious causes represent a frequent category and once diagnosed, may be managed effectively with targeted treatment. In addition, a range of non-infectious pathologies can result in dyspareunia, as lichen sclerosus, vulvodynia, chronic bladder pain syndrome / interstitial cystitis, Genitourinary Syndrome of Menopause (GSM) and endometriosis. Pelvic floor disorders such as urinary and fecal incontinence and prolapse are another relevant contributor to dyspareunia. Dyspareunia may also arise as a sequela of surgical interventions or radiotherapy often due to scarring or fibrosis.

Beyond these biomedical determinants, the biopsychosocial model provides a critical framework for understanding dyspareunia in general and postpartum dyspareunia in special. [4–6] Pain is not solely explained by anatomical injury but may be maintained by central sensitization, maladaptive coping strategies, and interpersonal or sexual dysfunction. Psychological comorbidities such as anxiety and depression lower pain thresholds and sexual desire, thereby exacerbating dyspareunia. Social and relational factors, including couple communication and cultural attitudes toward sexuality, further influence the pain experience.

Postpartum dyspareunia is a clinically relevant condition, with prevalence rates reported as high as 35% within the first year after delivery. [7,8]

Compared to cesarean section vaginal delivery is a well-known risk factor for postpartum dyspareunia. According to a recent systematic review, the prevalence of postpartum dyspareunia six to twelve months after delivery is 42% (95% CI, 31–56%) following vaginal delivery, 37% (95% CI, 28–46%) following instrumental delivery, and 26% (95% CI, 19–34%) following cesarean section. [9]

Vaginal delivery might be associated with perineal trauma including episiotomy, first- and second-degree tears, and severe third- and fourth-degree perineal tears, called obstetric anal sphincter injuries (OASIS). These injuries are well-documented risk factors for postpartum dyspareunia. [10] A register-based cohort study reported a prevalence of mild to moderate postpartum dyspareunia of 30.0% following second-degree perineal tears and 29.1% following episiotomy. Severe or unbearable postpartum dyspareunia was reported by 2.4% of women with a second-degree tear and 3.8% of women with an episiotomy. [11]

Other potential influencing factors are breastfeeding, psychosocial factors and pre-existing psychiatric disorders and dyspareunia. [3,12]

Breastfeeding is likely associated with increased postpartum dyspareunia due to reduced levels of estrogen, progesterone, and testosterone, which result in vaginal dryness, decreased elasticity, thinning of the mucosa, and diminished arousal, all of which predispose to painful intercourse. [13]

While instrumental delivery and perineal injuries are more likely to provoke superficial postpartum dyspareunia, estrogen deficiency and cesarean sections are more often associated with deep postpartum dyspareunia. [3,14–16]

Postpartum dyspareunia is known to decrease within the first year postpartum. A systematic review showed a prevalence of 42% (95% CI, 26%–60%) at 2 months, 43% (95% CI, 36%–50%) at 2–6 months, and 22% (95% CI, 15%–29%) at 6–12 months postpartum. [7] The usual postpartum care often ends after six to twelve weeks postpartum. Still, one in five women continues to suffer from postpartum dyspareunia one year later. This underscores the need for long-term postpartum surveillance and care.

Despite its frequency, the specific perinatal risk factors contributing to its development remain incompletely understood and are discussed with considerable controversy. Factors under investigation include the mode of vaginal delivery, the degree and management of perineal trauma, and the intrapartum use of oxytocin. [10,17,18]

The impact of postpartum dyspareunia extends beyond physical health, exerting deleterious effects on intimate relationships, sexual functioning, and overall quality of life. Importantly, postpartum dyspareunia constitutes one of the frequently neglected long-term sequelae of childbirth. [17,19,20] Still, most women do not discuss sexual disfunction with their health care providers but are willing to answer when asked. [21–23] This underscores the importance of assessing postpartum dyspareunia not only within the first six to twelve weeks postpartum but also up to one year or longer.

The aim of the present study was to investigate the frequency of postpartum dyspareunia one year postpartum in a cohort of primiparae. Particular emphasis was placed on evaluating potential perinatal influencing factors, including 1. Different vaginal birthing methods, 2. perineal injuries, and 3. the use of oxytocin during labor. A better understanding of these associations may facilitate the development of preventive strategies, inform clinical practice in perinatal care, and ultimately contribute to the reduction of postpartum dyspareunia and its associated burden.

Comments 5: The study design is based on data based between 1991-2006. These are very old data. Kindly justify the value of such studies. More recent data would be applicable our understaning.

Response 5: Agree.

Postpartum dyspareunia still is an underdiagnosed and neglected burden after childbirth. Most data focus on the early postpartum period (3-6months). Only few data are available which cover more than 6 months. But, dyspareunia, which lasts over six months, falls into the category of chronic pelvic pain syndrome. It is unlikely to disappear without adequate treatment. Detection of these conditions are essential. Studies on this topic are important and retrospective data demask the urgent need for prospective trials. The following arguments underline the importance of this work – even with old data:

- Large cohort study (n=3264) over a long period of time. This is unique and would be difficult to replicate today. The data were taken from an obstetric registry at a teaching hospital in Switzerland over a period of 15 years.

- The inclusion criteria were of a broad spectrum. Psychiatric disorders were not excluded.

- The participation rate during that period was very high. So, the study group reflects well the population. Today this can be referred as real data study.

- The obstetric standard of care hasn’t changed dramatically since 1999.

- Natural birth was an important element.

- Especially, episiotomies were already performed only when indicated and restrictively. A consequent perineal protection was performed. This makes the data still valuable for today. Especially, when having the recently published perineal care bundle in mind.

- Consistent manual perineal protection, also known as “hands-on” is traditionally standard in our midwifery training.

Comments 6: The variables to be studies should be itemized for clarify. What are the inclusion and exclusion criteria? Were patients who have premorbid psychological conditions or those who developed anxiety and depression after delivery excluded?

Response: 6: Thank you for these comments. The paragraph “study population” was adjusted, and inclusion / exclusion criteria were listed in detail and itemized:

Line 162 ff (clean version) / 205 (track-change version)

2.3 Study population

For this exploratory study, primiparae who completed the questionnaire one year postpartum were included in the study population.

The inclusion criteria were as follows:

· Primiparae at ≥37+0 weeks of pregnancy, cephalic presentation, and singleton pregnancies, regardless of comorbidities as psychiatric conditions, pre-existing chronic pain, or postpartum anxiety- and depression-disorder with

· Spontaneous vaginal deliveries or vacuum-assisted deliveries

· Manual perineal protection (“hands-on”)

· Restrictive, indicated episiotomies.

The exclusion criteria were as follows:

· Preterm birth before 37+0 weeks of gestation

· Multiparous women

· Breech presentation

· Cesarean sections

· Forceps delivery.

Variables studied:

· Maternal age

· Fetal birth weight

· Duration of the delivery

o Duration of the first stage of labor

o Duration of second stage of labor

o Duration of first and second stage of labor

· Birthing method

o Bed delivery (reference)

o Water delivery

o Other vaginal delivery

o Vacuum assisted delivery

· Perineal injury:

o Intact Perineum (reference)

o First- and second-degree perineal tear

o OASI (third- and fourth-degree perineal tear)

o Episiotomy

· The use of oxytocin

o No oxytocin (reference)

o During first stage of labor

o During the second stages of labor

o During first and second stage of labor

Postnatal pain management for all perineal injuries included oral or rectal analgesics, such as non-steroidal anti-inflammatory drugs (NSAIDs).

Between six and eight weeks postpartum, each woman attended a follow-up consultation with her gynecologist. During this visit, recovery was assessed, with particular attention given to wound healing in cases of perineal injury.

One year postpartum, every woman who had completed the initial questionnaires was asked to complete a final self-reported questionnaire. It took 5-10 minutes to complete. The questionnaire was sent to the woman regardless of her current health status or early postpartum recovery.

Comments 7: Could we have more details of the questionnaire? Were they validated? How were the subjects recruited for the study. Were the self-answered, if so how long did it take to complete the questionnaire? Since the study is to determine dysparunia, more details are required. Only one question pertaining to dysparunia has been included i.e. yes or no. Since the problem of dyspaunia is much wider, such an approach would test the validity of the results.

Response 7: Thank you for these questions and agree with your input.

- The translated questionnaire will be sent on request.

- The non-validated questionnaire with only one question on dyspareunia is a limitation. We focus on this more in detail in the limitation. Please see response 7, reviewer 2, Line 416 (clean version) / 507 (track change version)

- Please see the following background information.

Background information on the study and the questionnaire/ obstetric registry of a large women's teaching hospital:

Original Titel of the study: Integration of Alternative Birth Methods into Obstetric Care

The aim of this prospective observational study was to document all deliveries in order to evaluate maternal and neonatal outcomes.

The questionnaire was designed to address the research question and has been used unchanged for 15 years. No validated questionnaires were available for this research question. Question applied were among others: visual analog scale, Likert scale with 5-7 statements

Using a standardized questionnaire, both objective birth data (maternal and neonatal parameters) and subjective aspects (patient expectations, perceived/experienced pain, birth experience) were recorded. Data were entered into a dedicated database for the obstetric registry (SPSS 12).

The questionnaire included eight parts, covering the period from pregnancy until one year postpartum:

Before birth – completed by the patient
During birth – by midwife and patient
Immediately after birth – by patient and partner
Postpartum (days 2–4) – by patient and partner
Partogram – by midwife
Delivery room – by physician
Postpartum – by physician
One year after birth – by patient

The prenatal questionnaire (part 1) with a cover letter was provided at 24–28 weeks of gestation after the pregnant woman has been pre-registered for birth at the hospital. The questionnaire was returned at hospital admission.

Part 8 (the in this trial used questionnaire) was sent 12–15 months postpartum with a cover letter and prepaid envelope. It was self-reported and it took 5-10 minutes to complete.

Recruitment: The questionnaire was partly self-reported, partly answered by the medical staff from patient files. Every woman pre-registered for birth got to answer the questionnaire. Approx. 18000 questionnaires were distributed during 15 years (as long as the obstetric registry existed), out of which more than 17000 datasets resulted. About 9000 patients answered the 1y postpartum questions.

Comments 8: Kindly provide details of when the questionnaires were sent to subjects (time period). Explain the validation process of the questionnaires used in the study.

Response 8: Thank you for these comments. We added the information about the questionnaires:

Line 126 ff (clean-version) / 156 (track-change version)

Between 1991 and 2006 every woman pre-registered for birth go to answer the questionnaire. Roughly 18000 questionnaires were distributed, out of which more than 17000 datasets resulted. About 9000 patients answered the self-reported questionnaire one-year postpartum. The questionnaire was sent by post and took 5-10 minutes to complete. It was sent 12 months (+/- 2 weeks) postpartum to the women.

Line 245/246 (clean-version) / 293/294 (track change version)

The questionnaires were returned on average 15 months postpartum (SD +/- 2 months).

Validation:

As the trial started in 1991 no validated questionnaire was available. An internal content validation was performed by a multidisciplinary obstetric board.

Comments 9: Line 124: Please state what two decades refer to. References are required for Lines 135-136.

Response 9: Thank you for these points.

Line 136 (clean version) / 167 (track-change version) was changed to:

The Swiss standards of care for deliveries in teaching hospitals have remained comparable between 1991 and 2025.

Line 149 (clean version) / 183 (track-change version): references were added:

Ayerle GM, Mattern E, Striebich S, Oganowski T, Ocker R, Haastert B, Schäfers R, Seliger G. Effect of alternatively designed hospital birthing rooms on the rate of vaginal births: Multicentre randomised controlled trial Be-Up. Women Birth. 2023 Sep;36(5):429-438. doi: 10.1016/j.wombi.2023.02.009. Epub 2023 Mar 17. PMID: 36935270.

Gupta JK, Sood A, Hofmeyr GJ, Vogel JP. Position in the second stage of labour for women without epidural anaesthesia. Cochrane Database Syst Rev. 2017 May 25;5(5):CD002006. doi: 10.1002/14651858.CD002006.pub4. PMID: 28539008; PMCID: PMC6484432.

Walker KF, Kibuka M, Thornton JG, Jones NW. Maternal position in the second stage of labour for women with epidural anaesthesia. Cochrane Database Syst Rev. 2018 Nov 9;11(11):CD008070. doi: 10.1002/14651858.CD008070.pub4. PMID: 30411804; PMCID: PMC6517130.

Comments 10: Table 1: Foot notes to explain the abbreviations.

Response 10: Agree. Foot notes were added.

Degree	Extension of injury
First degree (I°)	Injury to perineal skin and/or vaginal mucosa
Second degree (II°)	Injury to perineum involving perineal muscles but not involving the anal sphincter.
Third degree (III° / OASIS)	Injury to perineum involving the anal sphincter complex
Grade 3a tear	Less than 50% of external anal sphincter thickness torn
Grade 3b tear	More than 50% of EAS thickness torn
Grade 3c tear	Both EAS and internal anal sphincter torn
Fourth degree (IV° / OASIS)	Injury to perineum involving the anal sphincter complex (EAS and IAS) and anorectal mucosa

OASIS: Obstetric anal sphincter injuries, EAS: external anal sphincter, IAS: internal anal sphincter

Comments 11: Results.

The weight of the newborn and prolonged labour (which may have warranted oxytocin augmentation) are useful variables to reflect on model of delivery and perineal injuries.

Response 11: Thank you for this comment.

The connection between fetal birth weight, prolonged labor and mode of delivery and perineal injuries is very interesting.

In an earlier publication (Zachariah RR, Forst S, Hodel N, Schoetzau A, Geissbuehler V. Is water delivery a good idea to prevent obstetric anal sphincter injuries in low risk primiparae? An exploratory study in a Swiss public teaching hospital. Eur J Obstet Gynecol Reprod Biol. 2024 Mar;294:39-42. doi: 10.1016/j.ejogrb.2023.12.024. Epub 2024 Jan 3. PMID: 38211455.) (out of the same cohort) we found an association between a birthweight above 4000g and OASIS (11.4% versus 5.6%).

The fetal birth weight and the duration of labor were equally distributed in the postpartum dyspareunia and no-dyspareunia groups; therefore, no univariable model was performed. In the multivariate model the birth weight was used, without showing an influence.

We additionally checked now for possible influences but only using a T-test to compare the duration of second stage of labor in the group with intact perineum and all perineal injuries together.

	Intact perineum	Perineal injuries	p-value
Duration of 2^nd stage of labor (min) (SD)	55 (45)	66 (54)	< 0.001
Fetal birth weight (g) (SD)	3288 (408)	3401 (424)	< 0.001

Even though statistically significant, the differences seem from a clinical point of few not relevant.

Further analysis can be performed on request.

Comments 12: Discussion.

The discussion is rather broad, touching on a range of topics. The relationship between perineal injuries and oxytocin use in 2nd stage is apparent. They may be related to each other. Could this also be included in the discussion.

Response 12: Thank you for this comment. We added the following sentences to the discussion:

Line 402 (clean version) / 489 (track change version)

If there is an association between the use of oxytocin, especially in the second stage of labor and the rate of second-degree perineal tears might be possible. Further research is needed to detect such an association.

As reviewer 2 pointed out a lot of suggestions for the discussion, it was re-written:

4. Discussion

This study examined the frequency of postpartum dyspareunia one year postpartum in a cohort of primiparous women with vaginal deliveries and explored potential influencing factors. The frequency of postpartum dyspareunia in this cohort was 15%. The frequency was evaluated using only one question asking for “strong pain” during sexual intercourse. Since this question was the only question, it is likely to underestimate the real prevalence. Still, this frequency is consistent with earlier studies reporting rates of up to 35%. [2,7,8] Despite the fact that in our study every sixth to seventh woman experiences postpartum dyspareunia a year postpartum, it remains a neglected consequence of childbirth. [17] The persistence of postpartum sexual pain has important implications not only for physical recovery but also for women’s psychological health, intimate relationships, and overall quality of life.

4.1 No influence of birthing method

Univariable analysis suggested that water deliveries were associated with a lower frequency of postpartum dyspareunia compared to bed deliveries. However, this influence was not confirmed in the multivariable analysis, which adjusted for potential confounders. This discrepancy suggests that factors beyond the birthing method, such as perineal injuries, labor management, breastfeeding or preexisting conditions, may play a more critical role in determining or developing postpartum dyspareunia.

The findings are consistent with published data. Several studies have demonstrated that the birthing method, while important for maternal satisfaction, is not itself a decisive predictor of sexual pain outcomes [15,18,32].

From a clinical perspective, these results suggest that vacuum extraction, often claimed to be more traumatic, is not necessarily associated with a higher rate of postpartum dyspareunia. This information might be useful for patient education.

Still, data about the effect of prenatal or postnatal counselling on the development of postpartum dyspareunia is non-existent. Prospective trials with validated questionnaires might give more insight in the development of postpartum dyspareunia.

4.2 Perineal injuries have an influence on postpartum dyspareunia

Perineal injuries emerged as a significant determinant of postpartum dyspareunia. Both, first- and second-degree perineal tears and OASIS, were strongly associated with higher postpartum dyspareunia frequencies compared to an intact perineum. These findings align with existing literature emphasizing the long-term impact of perineal trauma on sexual and reproductive health. [33–37]

Interestingly, mediolateral episiotomies did not show a statistically significant influence on postpartum dyspareunia in the multivariable analysis, and the impact of first- and second-degree perineal tears was more pronounced than that of OASIS. There are several explanations for this finding:

· In this hospital setting, mediolateral episiotomies were applied restrictively and only under selected indications, like fetal distress, risk for OASI or very tight perineum.

· Even though not intended, OASIS might be underdiagnosed as second-degree tear.

Whether the frequency of OASIS is under- or even over-diagnosed remains unclear. Surveys confirm neighter, mentioning an incidence between 1.74% - 6.1%. [29,38]

The introduction of the OASI care bundle has proven effective in reducing the rate of OASIS, without affecting cesarean or episiotomy rates. Importantly, women reported feeling empowered and supported, particularly due to clear communication and respectful care. Perineal protection and episiotomies, when performed appropriately, were not negatively experienced. [39] However, the effect of the OASI care bundle on postpartum dyspareunia remains unclear. Dedicated research is needed to evaluate whether these interventions also influence long-term sexual health outcomes, particularly if antenatal information has an influence.

The literature regarding first- /second-degree perineal tears and episiotomies remains inconsistent:

• Some studies report an association between these injuries and postpartum dyspareunia, [18,19,40,41] while others do not. [42–44]

• Selective episiotomy is associated with reduced perineal trauma [45] and has shown no significant association with prolonged perineal pain or postpartum dyspareunia. [45] This aligns with our findings.

• Some data indicate improved psychophysical health 12 months postpartum among women who underwent episiotomies. [19,46] Other data show similar outcomes for postpartum dyspareunia and sexual function when comparing episiotomies and first- and second-degree perineal tears. [19] Women with episiotomies often resumed sexual activity later than others. [42]

Together with previous studies, these findings suggest that episiotomies, selectively and restrictively used, do not increase the risk of postpartum dyspareunia. [45]

The difference between first- and second-degree perineal tears and episiotomies remains unresolved. Gommesen et al. identified a perineal length of less than 2 cm as a potential risk factor for postpartum dyspareunia. [19] A short perineal body may follow both OASIS and larger second-degree tears. Other studies have linked more extensive second-degree tears involving more than 50% of the bulbospongiosus muscle to prolonged postpartum dyspareunia or more severe postpartum pain. [40,41]

Suture techniques are another important factor. Previous research has compared continuous versus interrupted techniques.

Continuous suture techniques are associated with reduced short-term pain, less suture material, fewer complications, and better wound healing, but no clear long-term advantage for postpartum dyspareunia. [34,47,48]

In our cohort, both methods were employed. While continuous suturing is faster, interrupted sutures are often preferred in more complex injuries. Training and surgical expertise thus remain critical determinants of outcomes.

4.3 Oxytocin and its unknown influence

The use of oxytocin during labor did not show a statistically significant influence on postpartum dyspareunia in this study, although there was a non-significant trend toward increased risk when oxytocin was used during both the first and second stages of labor.

Oxytocin is a nonpeptide hormone widely employed for labor augmentation. Its effects extend beyond uterine contractions, influencing lactation, social behaviors, cognition, bonding, trust, and stress regulation. [49]

Its broader implications for perineal tissue, pelvic floor function, pain modulation, and postpartum mood, however, remain poorly understood. Some studies suggest that oxytocin administration may lead to increased pelvic floor muscle tone, potentially predisposing to higher rates of perineal trauma, episiotomy, and OASIS. [50,51] Other research has not found such associations. [52] If there is an association between the use of oxytocin, especially in the second stage of labor and the rate of second-degree perineal tears might be possible. Further research is needed to detect such an association.

Experimental studies have also suggested antinociceptive properties of oxytocin, with reduced pain sensitivity observed in some human trials, though reproducibility and clinical applicability remain uncertain. [53–55] Some trials have explored its use for pain relief. [49,56] But breastfeeding, which naturally elevates oxytocin levels, has not been shown to alleviate but increase postpartum dyspareunia. [57]

Rare data suggest associations between oxytocin dysregulation and postpartum mood disorders, [58] highlighting the complex interplay with cortisol and other neuroendocrine pathways. [59,60]

Given these uncertainties and its multifaceted roles across physical, psychological, and sexual health highlight the need for interdisciplinary research integrating obstetrics, endocrinology, urogynecology and pain science.

4.5 Limitation and future direction

This study's strengths include its large sample size and robust statistical approach, which allowed for adjustment of potential confounders. Over many years the obstetric team was very consistent; and there was a well-trained team in a teaching hospital. The obstetric standard of care, including manual perineal protection and restrictive use of episiotomies, diagnosis and treatment of tears, was well established and stayed comparable until today. This enhanced reliability even in these rather old data. Worldwide, the “OASI care bundle” was only recently introduced and contains the antenatal information to women, manual perineal protection, mediolateral episiotomy when indicated and the diagnosis and treatment of tears. [25,61] The standard of care in this study already used consequently three of the four recommended actions, namely manual perineal protection, mediolateral episiotomy and diagnosis and treatment of tears. This ensures comparability with modern practice.

However, the study has further limitations.

1. The analysis is retrospective.

2. The questionnaire used was not validated, as no questionnaire was available.

3. Postpartum Dyspareunia was not subclassified into deep and superficial forms.

4. The lack of detailed information on contributing factors such as preexisting dyspareunia, breastfeeding, hormonal status, BMI or psychological well-being.

At the time the questionnaire was selected, no validated questionnaire for an obstetric registry existed. A nationwide quality control mechanism in obstetrics had not yet been established. In this regard, pioneering had to be done.

As long-term (6 month and longer) postpartum dyspareunia should be considered and treated as a part of chronic pelvic pain syndrome there are several implications for future studies. Beyond the perinatal factors analyzed in this trial, there are the already discussed other suspected contributors. [3,33,62,63]

The biopsychosocial model is particularly relevant here. For example, women reporting higher levels of postpartum anxiety or depressive symptoms are more likely to also report sexual pain. This may be linked to altered pain perception thresholds and reduced sexual desire, which together reinforce postpartum dyspareunia. [64]

Future research should adopt prospective, multicenter designs with validated instruments for sexual health, e.g. female sexual function index. Greater emphasis should be placed on capturing psychosocial, hormonal, and lifestyle variables. Qualitative approaches could further enrich understanding by exploring women’s subjective experiences of postpartum sexuality. Interventional studies targeting prevention and treatment—such as pelvic floor rehabilitation, topical estrogen, counseling, or partner-based therapies—are urgently needed.

The potential benefits of antenatal education regarding postpartum dyspareunia warrant further exploration. Preparing women for the possibility of sexual pain, normalizing conversations about sexual and reproductive health, and offering early interventions could help mitigate the transition from acute to chronic pain. Early treatment of postpartum dyspareunia is essential to prevent the establishment of chronic pelvic pain syndromes.

Comments 13: Reference: They are comprehensive. Kindly format them.

Response 13: Thank you.

Formatting was performed: e.g.

1. Rogers, R.G.; Pauls, R.N.; Thakar, R.; Morin, M.; Kuhn, A.; Petri, E.; Fatton, B.; Whitmore, K.; Kinsberg, S.; Lee, J. An International Urogynecological Association (IUGA)/International Continence Society (ICS) Joint Report on the Terminology for the Assessment of Sexual Health of Women with Pelvic Floor Dysfunction. Neurourol Urodyn 2018, 37, 1220–1240, doi:10.1002/nau.23508.

Comments 14: Lines 144-164: Please write this in one paragraph.

Response 14: Thank you for this comment. The paragraph “study population” was changed and the adjusted to the reviewer’s proposal. Please see Response 6.

4. Response to Comments on the Quality of English Language

Point 1: The abstract requires improvement.

Response 1: The abstract was corrected. See Response 2

5. Additional clarifications

I°/II° perineal tears was changed in the whole text to first- and second-degree perineal tear.

As the conclusion required improvement (must be improved). The conclusion was re-written with a closer connection to the study results:

Line 460 (clean version) / 551 (track change version)

5. Conclusion

The findings highlight the prevalence of long-term postpartum dyspareunia. This underscores the need for further research.

· Prospective trials that include the full range of potential influencing factors (e.g., pre-existing dyspareunia and psychiatric disorders, BMI, perinatal factors, and postnatal factors such as breastfeeding) are essential.

· Validated questionnaires, such as the Female Sexual Function Index, should be employed.

· Comparable standards of obstetric care, including the use of the OASI care bundle, are recommended and may facilitate comparison across studies.

· The impact of the OASI care bundle on the development of postpartum dyspareunia requires further investigation.

· The effectiveness of different prevention strategies and management approaches also warrants evaluation.

As perineal injuries are a significant influencing factor in postpartum dyspareunia, ensuring perineal integrity during childbirth through evidence-based interventions—such as manual perineal protection techniques and selective episiotomy policies—is essential. However, their potential effect on the prevalence of postpartum dyspareunia remains to be demonstrated.

Structured training in repair techniques may also affect outcomes related to postpartum dyspareunia, though more research is needed.

Follow-up consultations extending beyond the usual six-to-twelve-week postpartum period appear essential for monitoring recovery and preventing long-term postpartum dyspareunia.

Prenatal counseling should include discussion of sexual health and potential postpartum challenges. Women consistently report that they prefer healthcare professionals to initiate these conversations. The effect of such counseling on postpartum dyspareunia remains to be established.

Postpartum dyspareunia not only represents a hidden and neglected condition but also lacks robust, prospective, and comparable research. By integrating this research into a global focus, obstetric care can advance beyond survival and safety to also improve long-term quality of life and intimate health for mothers.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses an important but under-researched issue: postpartum dyspareunia and its relationship to delivery mode, perineal trauma, and obstetric interventions. The large cohort size (n = 3264) and detailed perinatal records strengthen the study. The findings that perineal injuries, rather than delivery mode, are the primary predictors of dyspareunia are clinically meaningful and can guide obstetric practice.

The article is well written and generally well-structured, but there are methodological, analytical, and interpretive issues that should be addressed to improve the rigor and clarity of the manuscript.

Ensure consistent use of “dyspareunia” vs. “postpartum dyspareunia” throughout.
Figure 1 (regression model) is informative but could benefit from clearer labeling of reference categories.
The discussion is thorough but could be more concise, avoiding repetition across subsections.
Clarify whether retrospective consent procedures align with current standards, since only cover letters were used at the time.
Minor grammatical issues and occasional redundancy should be corrected during revision.
Outcome measurement depends on a single, non-validated item ("Do you experience very strong pain during sexual intercourse?"). This is likely to miss prevalence and to preclude milder/moderate dyspareunia.
Lack of validated sexual function tools (e.g., FSFI) reduces comparability with other studies.

8.Although the data set is large, the period is 1991–2006. Obstetric practice has altered since then (e.g., perineal protection bundles, episiotomy skills). Authors must state clearly how these temporal factors affect generalizability.

9.Key risk factors such as breastfeeding, hormone status, previous dyspareunia, BMI, and psychological health were not determined. Omission may lead to bias.

10.The paper does state this, but limitations must be emphasized more clearly.

11.The discussion overemphasizes conclusions (e.g., reassurance about vacuum deliveries) even when findings are borderline/non-significant.

12.The claim that OASIS was less influential than first- and second-degree tears is contrary to the evident and may be an underreporting or misclassifying of OASIS in earlier data. This needs to be cautiously qualified.

13.The alleged "trend" for increased dyspareunia with oxytocin is not statistically significant. The discussion needs to eschew overinterpretative speculation and instead highlight the need for further inquiry.
The study is valuable and addresses an important clinical problem, but revisions are needed to temper conclusions, clarify methodological limitations, and improve presentation.

Author Response

Comments 0: The manuscript addresses an important but under-researched issue: postpartum dyspareunia and its relationship to delivery mode, perineal trauma, and obstetric interventions. The large cohort size (n = 3264) and detailed perinatal records strengthen the study. The findings that perineal injuries, rather than delivery mode, are the primary predictors of dyspareunia are clinically meaningful and can guide obstetric practice.

Response 0: Thank you very much for the positive feedback.

Please see the changes made for improvement below.

Comments 1: Ensure consistent use of “dyspareunia” vs. “postpartum dyspareunia” throughout.

Response 1: Agree. The text was revised for consistent use of dyspareunia, when general spoken, e.g. introduction and postpartum dyspareunia, when referring to the postpartum period and the trial. For details, please see track-change version of the manuscript.

Comments 2: Figure 1 (regression model) is informative but could benefit from clearer labeling of reference categories.

Response 2: Thank you.

Figure 1 was adapted:

Figure 1. Logistic regression model predicting postpartum dyspareunia with Odds Ratios for respective predictor and corresponding 95% confidence intervals.

¹ OASIS: obstetric anal sphincter injuries

Intact perineum, bed delivery and no oxytocin were used as reference categories.

Comments 3: The discussion is thorough but could be more concise, avoiding repetition across subsections.

Response 3: Thank you for the comment. The discussion was in total adapted to all the different comments.

Line 310 ff (clean version) / 360 (track change version)