Effects of Auricular Acupressure Combined with Epidural Analgesia on Labor Pain: A Randomized Controlled Trial

Labor pain is a natural physiological process caused by uterine contractions and cervical dilation. It is a major physiological and psychological stressor that can trigger adverse neuroendocrine responses, potentially impacting both maternal and infant outcomes^1,2. Epidural analgesia represents the most effective pharmacological method for labor pain relief; however, it is associated with limitations such as breakthrough pain, motor blockade, and a well-documented association with epidural-related maternal fever (ERMF)^3,4,5. These limitations have stimulated interest in non-pharmacological approaches as potential adjuvants to epidural analgesia^6,7,8,9.

Auricular acupressure, a division of Chinese acupuncture, is based on the principle that specific points on the auricle correspond to body organs and funcions^6,7. Neurophysiologically, stimulating these points may modulate pain perception by activating the vagus nerve and inhibiting sympathetic nervous system activity, thereby reducing the pain stress response. Previous studies^{10,11,12,13,14,15,16,17} have reported the potential benefits of auricular therapy for labor pain; evidence regarding its combination with epidural analgesia remains limited.

This protocol describes a randomized controlled trial designed to address this evidence gap. The overall goal is to establish standardized methods for evaluating whether auricular acupressure improves the labor experience when combined with standard epidural analgesia. The technique offers several advantages over previous approaches, including rigorous blinding procedures, precise localization protocols for acupoints, and standardized outcome measures. This method will help researchers determine whether this combined approach is effective in improving labor outcomes across various clinical settings.

This study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital, Shanghai, China (NO.KS25200). The trial was registered in the International Traditional Medicine Clinical Trial Registry (registration number: ITMCTR2025000988). This study was designed and conducted according to the Consolidated Standards of Reporting Trials guidelines¹⁸. All participants provided written informed consent. The regents and the equipment used are listed in the Table of Materials.

1. Participant recruitment and enrollment

1. Screen potential participants according to inclusion and exclusion criteria.
   1. Recruit nulliparous women at term (37-40 weeks) admitted to the delivery ward.
   2. Consider the following inclusion criteria: primiparous women aged 20-40 years, gestational age 37-40 weeks, singleton pregnancy; cephalic presentation; absence of chronic diseases such as diabetes, cardiovascular diseases, hepatic or renal dysfunction; absence of pregnancy complications such as preeclampsia, gestational diabetes, or hemorrhage; no history of acupressure or acupuncture therapy; normal appearance of both auricles; and no history of allergy to alcohol or adhesive tape.
   3. Consider the following exclusion criteria: fetal distress; use of analgesic medication before or during the study period; and contraindications to epidural analgesia; skin infections on the auricles; known psychiatric disorders; a history of chronic pain or other pain-related condition that may influence pain perception.
2. Obtain informed consent
   1. Provide the participant with the detailed information sheet. Explain the study's purpose, procedures, and the voluntary nature of participants, including the right to withdraw at any time without penalty.
   2. Allow time for the participants to ask questions and consider.
   3. Obtain written informed consent.

2. Randomization and blinding

NOTE: An independent statistician generates a computer-randomized sequence using block randomization to assign participants to either the auricular acupressure group or the sham group.

1. Conceal assignments in sequentially numbered, opaque, sealed envelopes.
   NOTE: The research nurse opens envelopes after baseline data collection to reveal group assignment.
2. Maintain blinding of the participant, the outcome assessors, and the data analysts.
   ​NOTE: The acupressure practitioner cannot be blinded due to the nature of the intervention.

3. Baseline data collection

1. Record demographic data, including maternal age, height, weight, and gestational age.
2. Assess baseline pain score using the Visual Analog Scale (VAS), ranging from 0 (no pain) to 10 (extreme pain) at cervical dilation 2-3 cm.

4. Auricular acupressure application

1. Identify the acupoints according to standard auricular charts and locate Shenmen (TF4), Subcortex (AT4), Genitalia (TF2), and Sympathetic (AH6a) on both ears.
2. Clean the auricle with a 75% alcohol swab and allow it to air dry.
3. Apply Vaccaria seeds (Wangbuliu Xing Zi) attached to a 6 x 6 mm piece of waterproof tape to each identified acupoint using sterile tweezers (Figure 1).
4. Ensure the tape is firmly attached and centered on the acupoint.
5. Instruct the stimulation technique using the thumb and index finger, pressing firmly on each acupoint until a sensation of distension, numbness, or heat ("De Qi") is felt.
6. Stimulate each point for 1 min, every 60 min after epidural analgesia.
   NOTE: For the sham group, apply Vaccaria seeds to non-acupoints using identical instructions.

5. Epidural analgesia procedure

1. Prepare a solution containing 0.1% ropivacaine with 0.3 µg/mL sufentanil.
2. An experienced anesthesiologist performs the epidural analgesia with patients in the right lateral decubitus position using a 17-G Tuohy needle at the L2-3 interspace. Insert the 19-G wire-reinforced multi-orifice epidural catheter into the epidural space at a depth of 4 cm.
   CAUTION: Maintain strict sterility and monitor for local anesthetic toxicity. Ensure immediate availability of resuscitation equipment.
3. Initiate programmed intermittent epidural bolus of 10 mL every 50 min. Set the patient-controlled epidural analgesia bolus to 5 mL with a lockout interval of 15 min.

6. Outcome measurement

1. Assess and record the participant's VAS score at predetermined time points: cervical dilations at 2-3 cm before epidural analgesia (T1, baseline), 30 min after epidural analgesia (T2), and cervical dilation at 10 cm (T3).
2. Record the total consumption of local anesthetics, the incidence of breakthrough pain, the incidence of epidural-related maternal fever, the Apgar score, and maternal satisfaction.

7. Statistical analysis

1. Analyze data using SPSS 22.0 and GraphPad Prism 9.
   NOTE: Normally distributed measurement data are presented as the mean ± standard deviation, and comparisons between groups were made using the independent t-test. Non-normally distributed data are presented as median[interquartile range], and comparisons between the groups were made using the Mann-Whitney U test. Categorical variables are presented as rates or constituent ratios, and comparisons between groups were analyzed using the chi-square test or Fiser's exact test. For repeated measurement data, repeated measures analysis of variance (ANOVA) or a mixed-effects model was employed to account for time effects and group-by-time interactions.
2. Use appropriate statistical tests (t-test, u-test, chi-square test) with significance level p< 0.05.

In this study, fifty nulliparous women at term requesting epidural analgesia were included. Figure 2 shows the recruitment flow chart. The age, height, weight, and pregnancy week had no significance between the groups (Table 1). Figure 3 shows the changes in VAS pain scores at different times between groups. The VAS pain score was significantly lower in the auricular acupressure group after intervention compared to the sham group. The auricular acupressure group showed reduced local anesthetic consumption, a lower incidence of breakthrough pain, and higher maternal satisfaction, while Apgar scores and the incidence of epidural-related maternal fever were comparable between the auricular acupressure group and the sham group (Table 2).

Figure 1: Location of auricular acupoints (Shenmen, Subcortex, Genitalia, Sympathetic). Please click here to view a larger version of this figure.

Figure 2: Study flow chart. Abbreviations: AA, auricular acupressure; VAS, visual analog scale; ERMF, epidural-related maternal fever. Please click here to view a larger version of this figure.

Figure 3: Changes in VAS pain score at different times comparing the AA group and the sham control group. The data are presented as the mean ± SD. The P values are the results from a two-way repeated-measures ANOVA with time and group as two factors to be analyzed. The red line represents the AA group, the blue line represents the sham control group. T1, baseline (cervical dilation 2-3 cm); T2, 30 min post-epidural; T3, at full cervical dilation (10 cm). Please click here to view a larger version of this figure.

Table 1: Patient characteristics.

Table 2: Comparison of maternal and infant outcomes. The auricular acupressure group showed reduced local anesthetic consumption, lower incidence of breakthrough pain, and higher maternal satisfaction, while Apgar scores and epidural-related maternal fever were comparable between the auricular acupressure group and the sham group. Abbreviations: AA, auricular acupressure; ERMF, epidural-related maternal fever.

This randomized controlled trial protocol provides a standardized method for evaluating auricular acupressure as an adjunct to epidural analgesia for managing labor pain. Auricular acupressure is non-invasive, easy to perform, and humane; therefore, it is encouraged by the World Health Organization for the assistance of normal labor and delivery¹⁹. The integration of this non-pharmacological intervention with epidural analgesia represents a potential strategy to address known limitations of epidural analgesia, such as breakthrough pain and epidural-related maternal fever^3,4,5.

The successful implementation of this protocol hinges on several critical steps. First, the accurate localization of auricular acupoints is very important; misplacement could nullify the intended physiological effect. It is recommended that anatomical landmarks and standardized charts be used by certified acupuncturists to ensure precision. Second, meticulous adherence to the blinding procedure is crucial as any unintentional unblinding of outcome assessors could introduce significant measurement bias. Third, the use of a sham control group with non-acupoint stimulation represents a methodologically sound approach to account for the placebo effect²⁰.

The findings suggest that combining auricular acupressure with epidural analgesia tends to provide better pain control, which aligns with previous research indicating that auricular therapy can modulate pain perception through neurophysiological mechanisms^6,19,21. The lower incidence of breakthrough pain and higher maternal satisfaction in the auricular acupressure group further support the potential of this integrated approach to enhance the birth experience.

Despite its rigorous design, this protocol has several limitations that warrant acknowledgment. The most significant challenge is the inability to blind the interventionists administering the acupressure, a common issue in non-pharmacological trials. Although participants and outcome assessors were blinded, performance bias remains a potential concern. Furthermore, this is a single-center protocol, and the recruitment period is short; therefore, its generalizability to other institutions with different patient demographics or clinical practices needs confirmation. The VAS is a validated unidimensional measure of pain intensity; therefore, future studies should consider employing multidimensional pain assessment tools, such as the Angle-Labor Pain Questionnaire, which captures the sensory and affective dimensions of pain more comprehensively. The choice of sham control (non-acupoint stimulation) is methodologically sound, but it may not fully account for the entire nonspecific effects of the procedure.

This method offers advantages over previous approaches by providing detailed procedural guidance and rigorous methodology. Potential applications include investigating neuroendocrine mechanisms or long-term outcomes. In summary, this technique represents a valuable approach for integrating complementary therapies with conventional pain management strategies.