Ethics statement
The study protocol was approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (reference number: TJ-IRB20210755). The research conforms to the provisions of the Declaration of Helsinki30. All participants gave informed consent before the research, and their anonymity was preserved.
Study Design And Sample
A cross-sectional study was conducted using a convenient sampling method to select primiparas from obstetric wards of 10 comprehensive hospitals and three specialized hospitals from 7 provinces in China (Hainan, Zhejiang, Shanxi, Hubei, Guangxi, Xinjiang, Jilin) between November 2021 and March 2022. A total of 751 women entered the study. A self-administered online questionnaire was used to collect data. Women who had given birth within 72 hours at the study hospitals during the study period were recruited. The inclusion criteria were primiparous women aged ≥ 18 with a singleton pregnancy who were willing to participate in the study. The exclusion criteria were women who had psychological diseases or severe obstetric complications.
Measurement Of Psychological Birth Trauma
The Psychological Birth Trauma Scale (PBTS), a 15-item self-report scale, was used to assess the psychological birth trauma levels of the women. Each item is rated on a 5-point Likert scale from 1 (not meet at all) to 5 (exact match). The total score is between 15 to 75. A higher total score indicates stronger psychological birth trauma levels. The PBTS consists of four dimensions: being neglected (four items, Cronbach's α = 0.878), out of control (four items, Cronbach's α = 0.804), physiological emotional response (four items, Cronbach's α = 0.863), and cognitive behavioral response (three items, Cronbach's α = 0.904). Cronbach's α for the present study was 0.937.
Our research team developed, tested, and validated the PBTS to assess the psychological birth trauma of women, following a rigorous process of development and psychometric testing. We conducted a qualitative stage (generation of an item pool), which has been published31, and a quantitative stage (assessment of psychometric properties of PBTS). We conducted tests for content validity, item analysis, construct validity, split-half reliability, and internal consistency reliability32. Cronbach's α in this research was 0.874 and was judged acceptable. The results of confirmatory factor analysis were: χ2/df = 2.603, RMSEA = 0.067, CFI = 0.961, GFI = 0.929, NFI = 0.938, IFI = 0.961, TLI = 0.950 and RMR = 0.064, and supported the structure of four-factor model.
Measurement Of Social Support
The Chinese Mandarin Version of the Medical Outcomes Study Social Support Survey(MOS-SSS-CM)33 was used to assess the women's perception of social support; this scale has 20-item and includes 1 item evaluating the support network and 19 items assessing the availability of certain types of social support in emotional/informational, tangible, affectionate, and positive social interaction domains. It is a 5-point Likert scale, ranging from 1(none of the time) to 5 (all of the time), with a higher score indicating greater social support. The Cronbach's α and 2-week test-retest reliability for the Chinese version of the MOS-SSS were 0.98 and 0.84, respectively33. Cronbach's α for the present study was 0.973.
Measurement Of Childbirth Readiness Levels
The childbirth readiness scale (CRS) was used to assess the childbirth readiness levels 26. The CRS is an 18-item scale with four dimensions: self-management, information literacy, birth confidence, and birth plan. It is a 5-point Likert scale, ranging from 1 (strongly disagree) to 5 (strongly agree). The total score is between 18 to 90. A higher total score indicates greater childbirth readiness levels. The CRS has been validated in Chinese pregnant women with good reliability (split-half reliability = 0.88, Cronbach's α = 0.94) 26. In the present study, the CRS's Cronbach's α = 0.957.
Demographic Characteristics
The demographic characteristics included eight questions on participants' age, education, marital status, residence area, employment status, monthly household income (RMB, renminbi, Chinese yuan), pregnancy sleep status, and pregnancy exercise status.
Statistical Analyses
IBM SPSS Statistics 26.0 (IBM., Asia Analytics Shanghai) was used to conduct the statistical analysis. Two-tailed P < 0.05 was set as the significant level. All continuous variables were tested for normality, and they all confirmed normality. Independent t-test and one-way ANOVA were used to describe group differences in demographic characteristics of continuous variables. Pearson's correlations were used to examine the correlations between psychological birth trauma, childbirth readiness, and social support. The hierarchical multiple regression analysis was performed to explore childbirth readiness as a potential mediating role in the association between social support and psychological birth trauma. Control variables were entered in model 1. In model 2, social support was added, and in model 3 childbirth readiness levels were added as a mediator. The VIF less than 5 indicated that there is no severe multicollinearity. All the VIF values were < 5 in this study.
The mediation model was conducted using PROCESS 4.0 for the SPSS macro-program. The selection of control variables was based on the statistical of the univariate analysis. Social support was modeled as the independent variable, with psychological birth trauma as the dependent variable and childbirth readiness as the mediator. The total effect (path c), the direct effect (path c'), and the indirect effects (path a*b) were examined. 5000 bootstrapped samples based on bias-corrected confidence intervals were used to examine the indirect effect34. If the 95% bootstrap confidence interval does not include zero, the effect is regarded as significant.