Setting
The present study was performed from winter 2020 to the end of May 2020 in selected health centers and the maternity ward of 22 Bahman Hospital of Masjed Soleiman, Southwest of Iran.
Design
This study was a single-blind randomized clinical trial on 110 pregnant women referring to health centers and the maternity ward in Masjed Soleiman. Before commencement of the study, it was approved by the Ethics Committee of Ahvaz Jundishapur University of Medical Sciences, and the participants gave informed consent to participate in the study. All of these participants were pregnant women under the care of health centers and gynecologists. This clinical trial was retrospectively registered at the Clinical Trials Registration Center (Reference No.: IRCT20200126046266N1, retrospectively registered).
Inclusion and exclusion criteria
Inclusion criteria included age between 18 and 35 years, first pregnancy, single pregnancy, gestational age between 26 and 28 weeks, normal Body mass index, and willingness to participate in the study. Exclusion criteria included diseases such as pregnancy hypertension, gestational diabetes, heart problems, skeletal problems, medical prohibition to do exercise during pregnancy, absence from more than two sessions in the exercise programs and withdrawal from the study.
Randomization
The statistical population included all primiparous women referring to Masjed Soleiman health centers. Our method was convenience non probability sampling. Thus, from the beginning of the study, all women who had inclusion criteria and no exclusion criteria were included in the study, and this process continued until reaching the final sample size. Participants were registered by the researcher. These women were randomly assigned into two groups of control (n = 55) and intervention (n = 55) using the permuted block randomization method (blocks of six with a ratio of 1: 1). Participants were randomly selected using envelopes sealed by a health center staff member who was unaware of the nature of the study. The researchers and instructors involved in the training and the evaluators had no role in the randomization process..The study was single-blind. That is, the people evaluating the results of the study (midwifery staff working in the maternity ward of the hospital and the statistician) were blind to group assignment. Due to the nature of the study, blinding of the pregnant mothers to group allocation was not possible.
Intervention
In the intervention group, a Pilates exercise program, which was tailored to the conditions of pregnant women, was developed in coordination with a Pilates instructor and was performed twice a week for 8 weeks. Participants in the intervention were asked to choose a number from 6 to 20 in terms of the intensity of the effort to perform the exercises. Exercises started with light intensity and after two weeks of adjustment, the intensity increased. Because mothers’ physical strength during pregnancy is different and the intensity of exercise may be moderate for one mother but severe for another, causing severe sweating and fatigue. Of course, the intensity of the exercises had to be not more than 14 according to The Borg Rating of Perceived Exertion (RPE) [8], and if the exercise was estimated to be intense for the participant, she would not perform that exercise and would replace it with a lighter one. Before starting to exercise, participants were instructed to stop exercising if their perceived exertion increases above 14 on a scale from 6 to 20. After exercising all participants were asked to rate their perceived exertion on a scale from 6 to 20.
During the program, groups of 9 to 10 pregnant women were present to ensure a suitable space for exercise. Exercises with balls and fabric bands were also used during the sessions. Specific pelvic floor exercises, including contraction of the pelvic floor muscles, were performed intermittently with 5 to 10 repetitions. Each session included a warm-up phase (5 min), pregnancy specific Pilates exercises (25 min), and the phase of returning to a relaxed state (5 min) in which relaxation techniques were performed. After the exercise, the mothers would lay on their left side for 30 min and rested. The first 10 to 12 sessions of training were held in the presence of a sports coach with groups of 9 to 10 people in the gym. However, the last 4 to 6 training sessions were held at home under the supervision of an instructor due to the spread of the coronavirus. Participants’ adherence to the exercise regime was monitored through a daily exercise booklet. Once every two weeks, the control group received routine pregnancy advice over the phone and engaged in their daily activities and did not participate in any regular exercise program.
During and after childbirth care in both intervention and control groups was performed according to the standard and routine protocols of the hospital. During delivery, a checklist modified according to the conditions of each of the studied groups was completed.
Measurement instrument
Four instruments were used in the present study, including a two-section checklist, Borg Rating of Perceived Exertion (RPE), Visual Analog Scale (VAS), and Mackey Childbirth Satisfaction Rating Scale.
In this study, a checklist consisting of two sections was used to collect the required information. In the first section, the demographic information of the studied subjects was recorded. This information included the mother’s age, level of education, occupation, gestational age, and body mass index. In the second section of the checklist, obstetric information with regard to the research objectives was recorded. This included the severity of pain in dilatations of 3, 6, 8 and 10 cm, length of labor, type of delivery, oxytocin consumption, use of episiotomy, first- and fifth-minute Apgar score, and the mothers’ satisfaction with the childbirth experience. Intensity of labor pain was measured by Visual Pain Scale (VAS) consisting of a horizontal line 10 cm long with a score of zero for no pain and a score of 10 for maximum pain. To measure maternal satisfaction with childbirth, Mackey Childbirth Satisfaction Rating Scale was used, which included 22 questions in 4 sub-scales: the mother’s satisfaction with her performance, with the midwives’ performance, with infant status, and overall satisfaction with labor and childbirth experience. These are measured using a 5-point Likert scale including “very satisfied” (score 5), “satisfied” (score 4), “neither satisfied nor dissatisfied” (score 3), “dissatisfied” (score 2), and “very dissatisfied” (score 1). The total score obtained from this tool varies between 110 and 22. Scores between 22 and 55 are classified in the dissatisfied group, 88–56 in the desired satisfaction group, and 89 and above in complete satisfaction group. The intensity of exercise was assessed and recorded by the Borg Rating of Perceived Exertion (RPE). This scale consists of a 15-degree vertical line graded along its axis from 6 to 20 degrees. For moderate exercise, the American College of Obstetrics and Gynecology recommends the perceived severity of 14–13 (somewhat hard) to be used [11].
Visual pain measuring tool is the most widely used pain measuring tool in the world. In several studies abroad, the validity and scientific reliability of this tool has been confirmed and in Iran, the reliability of this scale has been confirmed with a correlation coefficient of r = 0.88 [14].
McKay Delivery Satisfaction Questionnaire has already been translated into Persian and used in Iran and its validity has been confirmed by content validity method and its reliability has been confirmed by calculating Cronbach’s alpha (α = 0.92) [15].
To calculate the sample size, the two-ratio comparison formula was used:
$$ n=\frac{{\left({z}_{1-a/2}+{z}_{1-\beta}\right)}^{2\ast}\left[{p}_1\;\left(1-{p}_1\right)+{p}_2\;\left(1-{p}_2\right)\right]\;}{{\left({p}_1-{p}_2\right)}^2} $$
Sample size was calculated based on the number of episiotomies after 8 weeks of Pilates exercise as in Rodriguez study. Where α = 0.05, β = 0.1 and based on the results of previous similar studies [16], we assumed P 1 = 0.1, P 2 = 0.42. Therefore, the initial sample size was considered 44, and taking into account the 20% attrition rate, the final sample size was estimated to be 55 in each group (110 people in total). Primary outcome included episiotomy. Secondary outcomes included severe labor pain, length of the first stage of labor, the length of the second stage of labor, and the type of labor, the need for oxytocin induction, first- and fifth-minute Apgar scores, and delivery satisfaction.
Statistical analysis
To analyze the data, descriptive statistical methods including frequency distribution tables, chart of central indicators and appropriate distribution were used to describe the study data. Quantitative data normality was checked by Kolmogorov-Smirnov test. The relationship between qualitative variables was assessed using Chi-square test. Within group relationship between quantitative variables was examined by paired t-test, and for between group examinations of quantitative variables, independent t-test and Mann-Whitney test were used. Because the distribution is normal, to describe 5 variables of age, gestational age at the beginning of the intervention, BMI, length of pregnancy, and weight of the baby, we used mean and standard deviation. For statistical tests, t-test was used. To describe other quantitative variables such as the lengths of the first and second stages of labor, pain intensity, first- and fifth-minute Apgar scores and oxytocin use, the middle (interquartile range) was used, and nonparametric tests such as the Mann-Whitney test were used. Kaplan-Meier test and Cox regression analysis were used for the entire duration of labor. In order to control possible confounding factors, analysis of covariance was used if necessary. Data analysis was performed with SPSS version 25.
