Participants
The study sample size was calculated by using G*Power 3 power calculations based on previous studies in which ice massage was applied to acupressure points during labor. Impact estimation was obtained from the findings of the study conducted by Hajiamini et al., who reported pain severity as 5.90 ± 1.84 in the ice massage group and 7.10 ± 1.64 in the control group 30 minutes after the ice massage application.12 In the present study, it was aimed to determine a similar difference. The sample size for each group was determined to be at least 47 individuals. Accordingly, 50 primiparas were assigned to the intervention group and the control group each. The power analysis performed showed that the sample size of the study had a power as α = 0.05, Power = 0.91, df = 98. The decrease observed in labor pain at 4-5 cm cervical dilatation compared to the control group had an impact size of 0.61.
The inclusion criteria for the primiparas were having a single healthy fetus, having a gestational age between 38 and 40 weeks, expecting vaginal delivery, having fetal cephalic presentation, having no chronic diseases, not having a high-risk pregnancy, being in stage 1 of childbirth, and having a 4-5 cm cervical dilatation. Pregnant women who were multiparous, had multiple pregnancies, had high-risk pregnancy, had delivery with complications, and came to the clinic after 4-5 cm dilatation were excluded from the study.
Single blind block randomization for pregnant women who met the inclusion criteria was achieved by using Sequence Generator method located under the subheading of Numbers at random.org website. In the program, two columns were created according to the sample size. The pregnant women were randomly assigned to Column 1 or Column 2 according to their registration number. The assignment of the columns to either the intervention group or the control group was done through a draw. Ice massage was applied to SP6 points of the pregnant women in the intervention group, while the pregnant women in the control group was provided with standard midwifery care.