Virtual Reality-Assisted Intraoperative Sensory Modulation on Postpartum Depression and the Kynurenine Pathway

1. Ethics Approval, Study Design and Sample Size This study was conducted after obtaining approval from the Düzce University Non-Interventional Clinical Research Ethics Committee (Date: 10.11.2025, Decision No: 2025/285) and with the support of the Düzce University Scientific Research Projects (BAP) Coordination Unit (Project No: [Project Number]). The study was carried out in accordance with the principles of the Declaration of Helsinki. The research was planned as a prospective, observational study. It was conducted between October 2025 and August 2026 at Düzce University Health Application and Research Center in patients undergoing elective cesarean section. The sample size was calculated using the G*Power software (Version 3.1.9.4), based on an ANOVA for repeated measures with between-subjects factors. Assuming 80% power (1-β), a Type I error rate of 5% (α = 0.05) and a medium effect size (f = 0.25), the minimum required total sample size was calculated as 98 for two groups and two repeated measurements (postpartum week 1 and week 6 depression scores), corresponding to 49 participants per group. Written informed consent was obtained from all participants after they were given detailed information about the aim and procedures of the study. ________________________________________
2. Study Population and Eligibility Criteria Inclusion criteria

• Pregnant women scheduled for elective cesarean section
• Age between 18 and 45 years
• ASA physical status I-II
• No contraindication to spinal anesthesia
• Signed written informed consent Exclusion criteria
• Anticipated need for postoperative intensive care unit (ICU) admission
• History of psychiatric or neurological disease
• Visual or auditory impairment
• Severe preeclampsia, eclampsia, or HELLP syndrome
• Perinatal loss (postpartum neonatal death)
• History of convulsions or epilepsy

1. Study Procedure and Grouping

A total of 98 patients who met the eligibility criteria were included and, in line with the observational design, were allocated into two groups:

• Group 1 (VR group, n = 49): Patients who underwent cesarean section under spinal anesthesia and received intraoperative virtual reality (VR) intervention via a VR headset to provide sensory modulation.
• Group 2 (Control group, n = 49): Patients who underwent cesarean section under spinal anesthesia and received standard clinical care without any VR application.

All patients underwent routine preoperative anesthetic evaluation in the anesthesia outpatient clinic. On the day of surgery, the State-Trait Anxiety Inventory-State form (STAI-I) was administered intraoperatively to assess anxiety levels.

In the operating room, after spinal anesthesia was performed and the sterile field was established, patients in Group 1 were fitted with a VR headset displaying preselected, nature-based, relaxation-oriented virtual reality content. The VR application was maintained continuously throughout the procedure until completion of skin closure, except for the moment of first maternal-infant contact. Patients in Group 2 received only standard clinical care and no VR headset was applied.

• Data Collection Tools and Measurements Study data were collected using demographic information forms, validated psychometric scales, and biochemical analyses. 4.1. Anxiety Assessment Patients' state anxiety levels were assessed using the State-Trait Anxiety Inventory-State form (STAI-I), originally developed by Spielberger et al. (1970) and adapted and validated in Turkish by Öner and Le Compte (1983). This self-report instrument consists of 20 items that evaluate the individual's current emotional state and intensity of anxiety at the time of assessment. 4.2. Postpartum Depression Assessment Postpartum depression was screened using the 10-item Edinburgh Postnatal Depression Scale (EPDS), developed by Cox et al. (1987) and validated in Turkish by Engindeniz et al. (1996). The EPDS was administered at postpartum week 1 and week 6 to evaluate depressive symptoms. 4.3. Patient Satisfaction Assessment Patient satisfaction with the operative experience was evaluated at the end of surgery using a Numerical Rating Scale (NRS). The NRS is a commonly used instrument providing a numerical rating from 0 (not satisfied at all) to 10 (completely satisfied). 4.4. Biochemical Measurements For biochemical analyses, residual plasma samples obtained from routine preoperative and 24-hour postpartum blood tests were used. After collection, blood samples were centrifuged under appropriate conditions, and plasma aliquots were stored at -80°C until analysis. Plasma levels of kynurenine, kynurenic acid, tryptophan and quinolinic acid were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kits, according to the manufacturer's instructions. ________________________________________
• Statistical Analysis Statistical analyses were performed using IBM SPSS Statistics (Version XX, IBM Corp., Armonk, NY, USA). The normality of continuous variables was assessed using the Kolmogorov-Smirnov or Shapiro-Wilk tests, as appropriate. For between-group comparisons, the independent samples t-test was used for normally distributed continuous variables, and the Mann-Whitney U test for non-normally distributed variables. Categorical variables were compared using the chi-square test or Fisher's exact test when expected cell counts were small.

Within-group changes over time (preoperative vs. postpartum measurements) were analyzed using the paired samples t-test for normally distributed data or the Wilcoxon signed-rank test for non-normally distributed data. A two-sided p value < 0.05 was considered statistically significant for all analyses.