Type of research and participants
In this cohort study, a part of a mixed methods research with an already published protocol , 204 primiparous women at 35-37 weeks of gestation were divided into the three groups of regular participation (attending 4-8 sessions), irregular participation (attending 1-3 sessions), and no participation in childbirth preparation classes. The study inclusion criteria consisted of living in Tabriz city, being primiparous, and having a gestational age of 35-37 weeks. The study exclusion criteria consisted of having a multiple pregnancy, being multiparous, non-cephalic presentation, obstetric problems such as placenta previa, inclination to deliver babies via elective cesarean section, history of major diseases such as cardiovascular diseases, diabetes, chronic hypertension, preeclampsia, history of depression requiring medicine, and occurrence of important stressful event in the past 6 months such as death of a close relative, separation from the partner, etc.
The sample size in this study was calculated based on the scores for the variable of postpartum depression using G Power software. According to the results obtained by Duncan et al. , on the relationship between prenatal education and postpartum depression, and considering M1 = 12.9 (the mean score for postpartum depression in control group), SD1 = 9.1, M2= 8.3 (the mean score for postpartum depression in the group participating in the childbirth preparation course), SD2 =6.1, two sided α =0.05, and power = 90%, the calculated number of participants for each group will be 61. Assuming an attrition rate of 10%, the final sample size will be 68 in each group and 204 in all.
Using cluster sampling, 7 of the 20 health complexes located in Tabriz, Iran, were randomly selected. Simple random sampling was then used to select the participants among all primiparous women admitted to these health centers affiliated with the selected complexes (Each health complex consisted of 4-5 health centers and the samples were selected from 29 centers). Using proportional allocation, the eligible women at 35-37 weeks of gestation were randomly selected from each center and divided into the three groups of regular participation (attending 4-8 sessions), irregular participation (attending 1-3 sessions) and no participation in childbirth preparation classes. The eligible women were enrolled and informed of the research objectives and methods. Informed consent was obtained from those who were willing to participate in the study. The socio-demographic and obstetrics questionnaires were completed in interviews held with the participants. The participants gave their phone numbers to the researchers and, one month after delivery, the researchers called the participants and asked them to visit their respective health centers to complete the Childbirth Experience Questionnaire (CEQ) and Edinburgh Postnatal Depression Scale (EPDS).
Data collection tools
The data were collected using socio-demographic and obstetrics characteristics questionnaire, CEQ and EPDS.
Socio-demographic and obstetrics characteristics questionnaire
The socio-demographic characteristics questionnaire consisted of items such as age, age of first sexual experience, educational qualifications, occupation, body mass index (BMI), spouse’s age, educational qualifications and occupation, level of support received from the spouse and marital satisfaction. The obstetrics characteristics questionnaire included items such as history of abortion, infertility, unwanted pregnancy, satisfaction with the fetal gender, type of delivery, place of delivery and delivery agent. The overall validity of this questionnaire was confirmed using face and content validity.
Childbirth Experience Questionnaire (CEQ 2.0)
This is a 23-item questionnaire that measures the childbirth experience of women. It consists of 4 domains including personal capacity (sense of control and personal feeling about childbirth and labor pain), professional support (information and midwifery care), perceived safety (sense of safety and childbirth memories), and participation (a woman’s ability to change her position to relieve pain during labor and childbirth). The tool consists of 20 four-choice items, and 3 items are scored using a visual analogue scale (VAS). The validity and reliability of this tool have been confirmed in a population of U.S. women. The responses included strongly agree (score 4), often agree (score 3), often disagree (score 2), and strongly disagree (score 1). Scores that are given using the visual scale are converted to scores of 1-4 (scores of 0-40 receive score of 1; 41-60 score of 2; 61-80 score of 3; and 80-100 score of 4). Items expressing negative concepts (experiencing severe pain, feeling tired, feeling afraid and having bad memories) receive negative scores. Higher mean scores indicate more positive childbirth experiences . The psychometric properties of this tool have been approved by Ghanbari Homayi et al . In this study, the reliability of this questionnaire was high (Cronbach’s alpha = 0.92).
Edinburgh Postnatal Depression Scale (EPDS)
This 10-item scale was developed by Cox et al. (1987) to measure prenatal and postpartum depression levels. It consists of 10 four-choice items. In some items, the options are arranged from low to high severity (items 1, 2, and 4) and in some they are arranged from high to low severity (items 3, 5, 6, 7, 8, 9 and 10). The scores given to each item range from 0 to 3 based on the severity of symptoms. The scores given to all items are summed up to produce the total depression score for each individual that can vary from 0 to 30 . The psychometric properties of this scale have been approved by Montazeri et al. . in this study, the reliability of this tool was measured using Cronbach’s alpha (alpha = 0.81).
After completing the questionnaires, data were analyzed in SPSS-21. The normality of the quantitative data was assessed using the Kolmogorov-Smirnov test. The homogeneity of the study groups in terms of demographic details was assessed using the one-way ANOVA, the Chi-squared test, Chi-squared test for trend, and Fisher's exact test. The study groups were compared in terms of postpartum depression and childbirth experience using the one-way ANOVA in the bivariate analysis and the general linear model with the adjustment of certain demographic variables in the multivariate analysis. P<0.05 was taken as the significance level.