1.1 Search strategy.
We selected relevant studies by searching PubMed, Embase, Web of Science, Cochrane Library, SinoMed, CNKI, WanFang Data and VIP. We also searched Chinese Clinical Trial Registry (https://www.chictr.org.cn/) and Clinical Trials.gov (https://clinicaltrials.gov/). All the databases were searched from inceptions to July, 2021. The search strategy consisted of 3 components: participant (parturition, parturitions, birth, childbirth, deliveries), intervention (auricular acupuncture, auricular acupressure) and study type (randomized clinical trial).
Study Selection
Two independent investigators (Z.W. and H. Z.) reviewed study titles and abstracts. Studies that satisfied the inclusion criteria were retrieved for full-text assessment.
1.2.1 Inclusion criteria. Relevant studies were included if the following criteria were met. (1) Types of studies: randomized controlled trials (RCTs) with or without blinding. (2) Participants: women intended vaginal delivery with a fetus at full term. (3) Types of intervention: with obstetric care routine, treatment groups that received auricular therapy (including auricular acupressure and auricular acupuncture) during the whole labour process or only the first stage of labour were included; we compared ear point therapy with obstetric care routine during the whole labour process or the first stage of labour. (4) Types of outcome measures: we included studies that measured pain level, visual analogue scale (VAS) score, duration of any stage of labour, maternal satisfaction, neonatal Apgar score, number of spontaneous delivery cases, number of caesarean section cases and postpartum blood loss.
1.2.2 Exclusion criteria. (1) Duplicate publications. (2) Studies with incomplete information which was still not available after attempts to contact the authors. (3) Studies combined other acupuncture therapies (manual/laser acupuncture, electroacupuncture, body acupressure, moxibustion and transcutaneous electrical nerve stimulation).