This study conducted and reported on the basis of the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement. A flow diagram of the randomized controlled protocol is shown in Fig. 1.This study registered on 15/01/2019 at https://en.irct.ir/trial/28120 adheres to CONSORT guidelines.
Study design and sample size
This randomized, controlled clinical trial was carried out after obtaining ethics approval. The study population was 123 primiparous women who referred to Alavi Hospital in Ardabil city in an official time during 2020–2021. Ardabil is the center of Ardabil province in the northwest of Iran. Since all participants were referred to a public hospital for delivery, they were approximately in the same socioeconomically class.
Inclusion criteria included married, normal medical and family conditions, having a normal, wanted, singleton and full-term pregnancy, vertex presentation, onset cervix dilatation, absence of neurological and psychological problems, having massage criteria (no skin disease and any lesions in the massage area). Exclusion criteria were feto-maternal high-risk situations.
Sample size was calculated 30 number for each study group using G Power software whit α = 0.05, power = 0.85, effect size = 0.71 and PASS Software with α = 0.05, power = 0.96, SD = 2, effect size = 0.5.
Allocation to study groups carried out by simple randomization method. Participants were chosen, one sealed envelope out of ten (5 massage group, 5 control group), offered by the researcher. This process was continued for all participants with inclusion criteria. From 123 pregnant women, 37 persons did not have the inclusion criteria, 20 women declined to participate, 8 women discontinued intervention (2 cases with full arrest, 3 cases of meconium defection, 3 cases of persistent occiput position), and one excluded from the analysis (refer to Fig. 1 for the CONSORT flow diagram). Finally, 60 women (in two groups of massage (30 person) and control (30 person)) completed the study process (see the CONSORT flow diagram). Written informed consent was obtained from all participants. Demographic information including the age, height, pre-pregnancy weight, current weight, educational level and job was collected with a demographic questionnaire. Validity of demographic questionnaire approved by 10 expert persons. Maternal height and weight were routinely measured when entering the maternity ward. Pre-pregnancy weight was obtained from the mother’s personal diary used for recording maternal care during pregnancy.
At the beginning of the study, in the active phase of labor, pain intensity and anxiety of participants were assessed. In the massage group from dilatation of 4 cm of the cervix to delivery, back massage was performed 3 times in dilatation of 5–7–9 cm based on Kimber massage instructions. The massage was done without the use of oil in the position desired by the mother in the LDR (Labor, Delivery, and Recovery) private room. This technique was applied between T10 and S4 according to Fig. 2  for 20 min each time. In order to control the amount of received massage and the uniformity of the intervention and to increase the accuracy of the study, massage, cervix examination and measurements were performed by the same researcher. In the control group, the routine maternity ward care was performed except massage. In addition, the researcher accompanied by participants in the control group as done for the massage group.
The primary outcome was the change in pain intensity and anxiety. Pain intensity was marked four times in each group according to the visual standard pain ruler. The ruler used had 10 cm length, which zero at one end indicates “no pain” and number 10 represents the “greatest possible pain”. The reliability and validity of the instrument were also confirmed [15, 16].
The participants’ anxiety was assessed at the beginning and the end of the study with the State‐Trait Anxiety Inventory (STAI) . In this questionnaire, the total numerical scores were obtained between 20 and 80 in a way that the anxiety rate of 20–31 attributed to mild anxiety, 32–42 to low-moderate anxiety, 43–53 to moderate-high, 54–64 to relatively severe, 65–75 to severe, and 76 and above to very severe anxiety. The reliability and validity of the Persian version of the STAI anxiety scale for pregnancy were studied by Mortazavi et al.  in a sample of Iranian women. The duration of labor was calculated from the time of entering into the active phase of labor until the time of fetal birth. The Secondary outcome was the determining appropriate cervical dilatation for massage. The appropriate cervical dilatation for massage was considered as a dilatation with highest reduction in pain intensity.
Data were analyzed using SPSS software version 26. The categorical variables of demographic characteristics were analyzed by Chi-square and the independent t-test was used for continuous variables. The Analysis of Covariance (ANCOVA) was used to compare the means of pain and anxiety data. The p < 0.05 was considered as significant.
After obtaining permission from the Iran National Committee for Ethics in Biomedical Research (IR.ARUMS.REC.1396.204). Study registered in the Iranian Registry of Clinical Trial (IRCT20140118016255N5) in15/01/2019, https://en.irct.ir/trial/28120. Then we conducted the study in Alavi hospital in Ardabil-Iran. Before completing the questionnaire, participants were informed about the objectives of the study, and informed consent was obtained from all participants included in the study. They were assured of the confidentiality of information.