2.2.1 The first stage of labour
2.2.1.1 VAS score in latent phase and active phase Four studies assessed the VAS score in the latent and active phase of labour. We adopted a random effect model, because heterogeneity between the studies was observed (p <0.01; I2=99%, 96%). Pooled analysis of the 4 studies showed that VAS score in auricular acupressure groups was significantly lower than the controls during latent phase (MD=-2.56, 95%CI: [-4.26,0.86], p =0.003). However, there were no significant differences in active phase (Figure 4). Sensitivity analysis indicated that the results were robust.
2.2.1.2 Maternal satisfaction in latent phase Three studies reported maternal satisfaction in latent phase. There was no between-study heterogeneity (I²=0%), so a fixed effect model was conducted. The pooled analysis indicated that satisfaction rate in the auricular acupressure groups was significantly higher than in the control groups (RR=1.29, 95%CI [1.18, 1.41],p <0.05) (Figure 5). Sensitivity analysis indicated that the results were robust.
2.2.1.3 Duration of the first stage of labour Pooled analysis of the 6 studies that reported duration of the first stage of labour showed a significant reduction in duration of the first stage when participants were treated with auricular acupressure compared with the controls (MD=-1.24, 95%CI [-1.86, -0.61, p <0.05]), with significant between-study heterogeneity (I2=97%) (Figure 6). Sensitivity analysis indicated that the results were robust.
2.2.1.4 Neonatal Apgar score Four studies reported neonatal Apgar score in both 1 minute and 5 minutes with significant heterogeneity (I2=87%) and no heterogeneity (I2=0%) respectively. We pooled studies and found no significant difference between groups (Figure 7). Sensitivity analysis indicated that Li et al.[18] appeared to add significant heterogeneity to 1 min Apgar score. Removing this study eliminated this heterogeneity (I2=0%), and changed the effect size of the pooled result (Z = 0.27, P = 0.79) , but there was still no significant difference between groups.