Effects of chewing gum and LI4 acupressure on gastrointestinal recovery after cesarean section: A randomized controlled trial

Abstract

Background

Postoperative gastrointestinal dysfunction is a frequent complication after cesarean section (CS), delaying recovery and causing discomfort. This study assessed the effects of chewing gum (CG) and LI4 acupressure—each compared with routine care—on gastrointestinal recovery after elective CS.

Methods

In this three-arm randomized controlled trial, 105 women undergoing elective CS were randomly allocated to CG plus routine care, acupressure plus routine care, or routine care alone (n = 35 each). Interventions were applied three times daily for two days. Primary outcomes were time to first gas passage and defecation; secondary outcomes included time to mobilization, postoperative abdominal pain (measured at six time points), and nausea/vomiting incidence. Analyses employed Kaplan–Meier survival curves, repeated-measures ANOVA, and chi-square tests.

Results

Both CG and acupressure groups showed significantly faster recovery than routine care, with shorter times to first gas passage, defecation, and mobilization (all p < 0.001). No significant differences were observed between CG and acupressure for these measures. A significant time × group interaction for pain (p = 0.025) indicated greater and more sustained relief in the acupressure group (all p < 0.05 vs. other groups). Nausea and vomiting rates were lower in intervention groups, though differences were not statistically significant.

Conclusions

Chewing gum and LI4 acupressure each significantly enhanced postoperative gastrointestinal recovery after CS compared with routine care, while acupressure provided superior pain control. These simple, non-pharmacological methods may improve maternal recovery and comfort.

Trial registration: Iranian Registry of Clinical Trials,

IRCT20200206046395N3 (https://irct.behdasht.gov.ir/).

1. Introduction

Cesarean Section (CS) is one of the most common abdominal surgeries globally, with a prevalence of approximately 21 %. ¹ Despite its frequency, CS is associated with several postoperative complications, notably gastrointestinal dysfunction, which affects 10 %–30 % of patients.² This dysfunction can manifest as delayed gas and stool passage, absent bowel sounds, distension, pain, nausea, vomiting, anorexia, and food intolerance.3, 4, 5 These symptoms impact maternal and neonatal well-being⁶ and may lead to ileus,⁷ poor wound healing,⁸ and prolonged hospital stays,⁹ significantly increasing healthcare costs—up to $1.46 billion annually in the U.S. .^10,11

Several contributing factors to postoperative gastrointestinal impairment include intraoperative bleeding, anesthesia type, opioid use, surgical manipulation, and metabolic disturbances.¹² Although medications like Simethicone, Ulimovelin, Alvimopan, and Naldemedine exist, their limited effectiveness and side effects reduce clinical use.^13,14 Thus, early detection and non-pharmacological interventions are encouraged.¹³ Recommended strategies include coffee intake, chewing gum (CG), walking, acupuncture, and acupressure.¹⁴

Acupressure, a Traditional Chinese Medicine technique, is based on stimulating acupoints along energy meridians (Qi) through finger pressure. It is simple, non-invasive, and low-cost.¹⁵ Common gastrointestinal acupoints include SP9, ST36, RN12, SP6, LI4, and others.^16,17 Research has shown promising effects. Soylu and Kartın found that acupressure reduced postoperative pain and accelerated bowel movement post-laparoscopy.¹⁸ Abadi et al. reported improved outcomes with ST36 and LI4 stimulation, reducing time to gas passage and bowel sounds.¹¹ A systematic review also supports acupressure’s role in reducing postoperative nausea and vomiting,¹⁹ although findings are mixed—Hsiung et al. found no significant benefit following gastrectomy.²⁰

CG may also enhance postoperative bowel function by mimicking mastication, increasing saliva, gastrin, and pancreatic enzyme secretion—thus stimulating peristalsis.21, 22, 23 CG has shown benefits across various surgeries, including hysterectomy,²⁴ Whipple,⁴ ileostomy,²⁵ laparotomy,²⁶ and lumbar fusion.⁸ A meta-analysis of 32 trials (n = 4999) confirmed that CG reduces time to first gas passage and defecation post gastrointestinal surgery.²⁷

Although the individual effects of CG and acupressure have been previously investigated, direct comparisons between these two interventions—particularly in the context of CS—remain scarce. To the best of our knowledge, no prior study has directly compared the effects of LI4 acupressure and CG on gastrointestinal recovery after CS within a single trial.

Therefore, this randomized controlled trial aimed to evaluate the effectiveness of CG and LI4 acupressure—each compared to routine care—in promoting postoperative gastrointestinal recovery among women undergoing CS. We hypothesized that both interventions (CG and acupressure) would significantly enhance gastrointestinal recovery compared to routine care.

2. Methods

2.1. Trial design and registration

This study is a prospective, single-center, parallel, randomized controlled clinical trial. It received approval from the Ethics Committee of Shahroud University of Medical Sciences on January 10, 2024, and was registered on January 21, 2024 in Iranian Registry of Clinical Trials (https://irct.behdasht.gov.ir) with the identification code IRCT20200206046395N3. Throughout the research, the ethical standards set by the Institutional Research Committee were followed in accordance with the Declaration of Helsinki. Participants willingly provided informed consent by signing the consent form.

2.2. Participants

The study involved 105 pregnant women who were eligible for elective CS with spinal anesthesia and had visited Bahar Hospital in Shahroud. Inclusion criteria were being at least 18 years old, having the ability to read and write, being able to chew, and having a healthy acupressure intervention area (without skin rashes, arthritis, local infections, etc.). Exclusion criteria included changes in the anesthesia method, loss of consciousness after CS, abnormal bleeding during or after CS, intestinal damage during CS, and a previous history of gastrointestinal disease.

2.3. Sample size

The sample size calculation was based on previous randomized controlled trials by Abadi et al.¹¹ and Ledari et al.,²⁸ which investigated the primary outcome: time to first passage of flatus after CS.

• •In Abadi et al., the mean (±SD) time was 17.7 ± 6.0 h in the acupressure group and 25.75 ± 9.1 h in the control group, yielding a mean difference of 8.05 h and an effect size (Cohen’s d) of approximately 1.02.
• •In Ledari et al., the mean (±SD) was 25.02 ± 5.8 h in the CG group and 31.08 ± 9.7 h in the control group, corresponding to a mean difference of 6.06 h and an effect size of approximately 0.74.

Using the largest observed effect size (d = 1.02) in G*Power software (version 3.1.9.7), with a two-tailed α = 0.05 and power (1–β) = 0.80, the minimum required sample size was calculated as 28 participants per group. To account for an anticipated dropout rate of exactly 20 % and to increase statistical reliability, we planned for 35 participants per group. Although this trial employed a three-arm design, no prior studies directly compared all three interventions; therefore, the calculation was conservatively based on the largest pairwise difference between an intervention and routine care group. This approach ensured adequate power to detect clinically meaningful differences, with subsequent analyses accommodating the three-arm structure to evaluate all group comparisons.

2.4. Randomization

Participants were randomly allocated to three groups (A: acupressure + routine care, B: chewing gum + routine care, C: routine care) in a 1:1:1 ratio using block randomization with a block size of six, generated by an independent statistician using a computerized random number generator (Random Allocation Software). The randomization list was placed in sequentially numbered, opaque, sealed envelopes to ensure allocation concealment. Each envelope was opened sequentially, and only after the participant had signed the consent form and completed baseline assessments.

2.5. Masking

Due to the nature of the interventions, participants and the researcher delivering the interventions could not be blinded. However, the outcome assessor and the data analyst were blinded to group assignments to minimize potential bias in data collection and statistical analysis.

2.6. Primary outcome

The primary outcomes of the study were the first instance of passing gas and the first instance of defecation after CS. These indicators are commonly considered in most studies as a measure of improvement in gastrointestinal function.

2.7. Secondary outcomes

The secondary outcomes included the time of first mobilization after CS, the number of instances of nausea and vomiting, and the level of abdominal pain. Abdominal pain was assessed using a 10-point Visual Analog Scale (VAS), where 0 indicated no pain, 1 to 3 indicated mild pain, 4 to 7 indicated moderate pain, and 8 to 10 indicated severe pain. The VAS is widely used in clinical studies due to its established validity and reliability.29, 30, 31

2.8. Intervention

After the mothers were transferred from the operating room to the obstetrics and gynecology department, 2 h after CS, participants in the intervention groups received either acupressure or CG in addition to the routine care. In contrast, those in the routine care group received only standard postoperative care. CG and acupressure interventions were administered at regular intervals over two consecutive days, three times a day, for 20 min each session, totaling six interventions (120 min). Below is a detailed description of the interventions.

In the acupressure + routine care group, mothers received acupressure at the LI4 point, based on the opinion of an acupressure expert and previous studies.^3,11,32 Initially, the researcher created a calm environment for the mother by closing the door and windows and instructing her to lie comfortably on the bed. After washing and drying his hands, the researcher put on disposable gloves. The targeted massage site was the LI4, a primary point of the large intestine meridian, located on the back of the hand between the first and second metacarpals. The researcher applied pressure to the LI4 using his thumb, adjusting the pressure to the mother’s tolerance for two minutes. This pressure was applied through clockwise and counterclockwise rotations of the thumb. Following this, the pressure was released for two minutes, and the point was manipulated for an additional minute to maintain meridian stimulation. Each procedure cycle lasted five minutes and was repeated four times on both hands.

In chewing gum + routine care group, the researcher provided each mother with 12 pieces of gum, manufactured by Kurdistan-Iran Turpentine Manufacturing Company. Each mother was instructed to chew two pieces of gum three times for 20 min per session. Additionally, mothers received a motivational phone call encouraging them to complete the interventions and reminding them of the scheduled times.

In routine care group, standard care after surgery to improve the health and well-being of both the mother and baby included the following: monitoring vital signs, providing wound care, monitoring the uterus, encouraging early mobilization, offering emotional support, recommending the consumption of liquids and fiber, suggesting active and passive movements in bed, and using NSAIDs for pain relief as well as antiemetics for alleviating nausea and vomiting.

2.9. Data collection

All demographic and clinical information was collected based on participants' statements and medical records. A blinded evaluator assessed abdominal pain in mothers following each intervention. Each mother was provided with an analog clock, a notebook, and a pen and was asked to record the time of first defecation, passing gas, and mobilization after CS, as well as the number of instances of nausea and vomiting. The evaluator collected the notebook at the time of the mother's hospital discharge.

2.10. Statistical analyses

All analyses were performed using SPSS version 25 (IBM Corp.), with statistical significance set at p < 0.05. Continuous data were assessed for normality using the Shapiro-Wilk test and are presented as mean ± SD for normally distributed variables, or median (Q1, Q3) for non-normally distributed variables. Categorical variables are reported as n ( %). Group comparisons were conducted using Pearson's chi-square test or Fisher's exact test for categorical data (e.g., incidence of nausea/vomiting), and one-way ANOVA with Tukey's post hoc test for normally distributed continuous variables. For longitudinal outcomes (e.g., abdominal pain), repeated-measures ANOVA with Greenhouse-Geisser correction was used to evaluate time effects, group effects, and time × group interactions. Time-to-event data (e.g., time to first mobilization) were analyzed using Kaplan-Meier survival curves and compared using the Log-rank (Mantel-Cox) test, with Bonferroni correction applied for multiple pairwise comparisons. All analyses were conducted on participants who completed the interventions and included appropriate assumption checks (e.g., Levene’s test for homogeneity of variance and Mauchly’s test for sphericity).

3. Results

3.1. Sample flow and baseline data

One hundred forty-nine pregnant women were assessed for trial eligibility, with 44 excluded for various reasons. As a result, 105 women were enrolled and divided into three groups: CG plus routine care Group (n = 35), Acupressure plus routine care Group (n = 35), and routine care Group (n = 35). Six mothers were lost to follow-up during the post-cesarean section period. The study's flow chart is depicted in Fig. 1. The groups showed good matching for demographic and clinical data during the initial assessment (P > 0.05; see Table 1).

Fig. 1.

Flow diagram of the study.

Abbreviation: CG, chewing gum.

Table 1.

Demographic and clinical characteristics of participants.

Variables	Group (Mean ± SD)			P value
	Acupressure + Routine care (n = 33)	CG + Routine care (n = 33)	Routine care (n = 33)
Age (years)	25.15 ± 4.54	26.63 ± 4.24	26.39 ± 4.48	0.34†
BMI (kg/m2)	27.94 ± 4.74	28.60 ± 3.66	28.85 ± 4.12	0.64†
Underlying diseases (Yes/No)	8/25	11/22	9/24	0.70*
History of surgery (Yes/No)	11/22	17/16	8/25	0.06*
History of childbirth (Yes/No)	5/28	6/27	8/25	0.63*
Operation time (minutes)	59.84 ± 11.48	57.87 ± 14.36	58.33 ± 14.01	0.82†
Anesthesia time (minutes)	79.24 ± 11.60	77.72 ± 16.15	79.09 ± 17.47	0.90†
length of stay in the PACU (minutes)	66.66 ± 11.22	65.00 ± 9.68	64.54 ± 9.54	0.67†
Length of hospital stay (hours)	51.63 ± 7.73	52.36 ± 9.40	53.90 ± 10.61	0.62†
Cause of cesarean section, n (%)				0.51‡
Previous C-sections	7 (21.2)	9 (27.3)	8 (24.2)
Multiple Gestations	5 (15.2)	4 (12.1)	3 (9.1)
Placenta previa	11 (33.3)	6 (18.2)	5 (15.2)
Fetal presentation	3 (9.1)	3 (9.1)	3 (9.1)
Uterus abnormality	2 (6.1)	4 (12.1)	1 (3.0)
Maternal Request	5 (15.2)	7 (21.2)	13 (39.4)
Number of patients who received analgesic requirements, n (%)
3 times	16 (48.4)	18 (54.5)	18 (54.5)	0.63‡
4–6 times	15 (45.4)	11 (33.3)	10 (30.3)
≥7 times	2 (6.2)	4 (12.2)	5 (15.2)
Number of patients who received anti-nausea medicine, n (%)				0.30*
3 times	18 (54.5)	19 (57.6)	11 (33.3)
4–6 times	10 (30.3)	9 (27.3)	13 (39.4)
≥7 times	5 (15.2)	5 (15.2)	9 (27.3)

BMI, body mass index; CG, chewing gum; PACU, post anesthesia care unit; SD, standard deviation.

^⁎Chi-square.

^†Analysis of variance.

^‡Fisher’s exact test.

3.2. Main outcomes

Kaplan–Meier analyses revealed significant differences among the three groups in terms of time to first passing gas, defecation, and mobilization (χ² = 30.686, df = 2, p < 0.001; χ² = 33.552, df = 2, p < 0.001; and χ² = 32.226, df = 2, p < 0.001, respectively). In all three parameters, both intervention groups (Acupressure + routine care and CG + routine care) achieved significantly faster recovery compared to the routine care only group (all p < 0.001, Bonferroni-adjusted). However, there were no statistically significant differences between the two intervention groups. Detailed statistical comparisons are presented in Table 2, with the Kaplan–Meier curves provided in Supplement 1.

Table 2.

Comparison of the time to first passing gas, defecation, and mobilization of the groups after CS.

Outcomes	Groups median (Q1, Q3)			P value*	Two-by-Two comparison
	Acupressure + Routine care (n = 33)	CG + Routine care (n = 33)	Routine care (n = 33)		Routine care vs Acupressure + Routine care	Routine care vs CG + Routine care	Acupressure + Routine care vs CG + Routine care
Time to first passing gas (h)	34 (24, 38)	30 (24, 35)	41 (32, 46)	<0.001	P < 0.001†	P < 0.001†	P = 0.131†
Time to first defecation (h)	35 (33, 38)	36 (35, 39)	41 (39, 45)	<0.001	P < 0.001†	P < 0.001†	P = 0.233†
Time to first mobilization (h)	22 (18, 24)	24 (21, 26)	28 (25, 30)	<0.001	P < 0.001†	P < 0.001†	P = 0.334†

CG, chewing gum; CS, cesarean section; h, hour; Q1, first quartile; Q3, third quartile.

^⁎Log-rank (Mantel–Cox) test.

^†Pairwise comparisons using Bonferroni-adjusted log-rank test.

Postoperative abdominal pain decreased over time across all study groups (Fig. 2). A statistically significant group × time interaction was observed (F(3.019, 144.9) = 3.19, p = 0.025), indicating that the trajectory of pain reduction differed between the groups. Post hoc analyses at each measurement time point (Supplement 2) revealed that the Acupressure + routine care group consistently demonstrated significantly lower mean VAS scores compared with both the CG + routine care and routine care only groups from the first post-intervention assessment onward. No significant differences were observed between the CG + routine care and routine care only groups at any time point. Refer to Fig. 2 for a visual representation of these between-group differences.

Fig. 2.

Changes in mean (±SD) VAS pain scores over time by study group. VAS pain scores were recorded at multiple time points before and after the interventions. The data are presented as means with standard deviations. CG, chewing gum; T0, before intervention; T1, after the first intervention; T2, after the second intervention; T3, after the third intervention; T4, after the fourth intervention; T5, after the fifth intervention; T6, after the sixth intervention; VAS, visual analog scale.

The incidence of nausea and vomiting after CS was numerically lower in the Acupressure + routine care and CG + routine care groups compared to the routine care only group. However, these differences were not statistically significant (P > 0.05 for both outcomes). See Supplement 3 for detailed data.

4. Discussion

4.1. Summary of main results

This study found that both CG and LI4 acupressure, when added to routine postoperative care, significantly enhanced gastrointestinal recovery after CS compared to routine care alone. Specifically, both interventions reduced the time to first gas passage, defecation, and mobilization. In addition, acupressure was associated with greater reductions in postoperative abdominal pain, particularly on the second postoperative day. Although reductions in nausea and vomiting were observed in both intervention groups, these differences did not reach statistical significance. These findings support the use of CG and acupressure as simple, non-pharmacological adjuncts to routine care, with acupressure offering an added benefit in pain management.

4.2. Agreement and disagreements with other studies or reviews

The findings of this study are broadly consistent with previous research highlighting the effectiveness of CG and acupressure in enhancing postoperative gastrointestinal function.33, 34, 35, 36, 37 Several studies have demonstrated the beneficial role of CG in reducing the time to first flatus and bowel movement following abdominal surgeries. For instance, Sinz et al.²⁷ conducted a systematic review showing that CG significantly shortens gastrointestinal recovery time regardless of surgery type. Similarly, Zargani et al.³⁸ reported reduced time to first gas and defecation after CS, and Malek Hosseini et al.³⁹ found that CG alleviated postoperative ileus symptoms following burn surgeries. These align with our findings, although Kanza Gül et al.⁶ did not observe similar benefits of CG in a study comparing it with coffee and routine care, likely due to methodological differences such as sample size, intervention protocol, and patient variability.

The observed benefits of acupressure at the LI4 point in our study also align with prior evidence. A study conducted at Vali-Asr Hospital demonstrated that LI4 acupressure significantly reduced the time to first flatus and defecation after CS.¹¹ Likewise, Kırca and Gül reported earlier return of bowel function in women receiving acupressure at LI4 and ST36 compared to control.³ In addition to gastrointestinal improvements, our study noted significantly lower pain scores in the acupressure group—a finding supported by previous studies across various surgical contexts, including coronary angiography,⁴⁰ laparoscopic cholecystectomy,⁴¹ hysterectomy,⁴² and ENT procedures.⁴³

Although the reduction in nausea and vomiting observed in the CG and acupressure groups was not statistically significant, the trend aligns with earlier studies suggesting that these non-pharmacological interventions may help reduce postoperative nausea and vomiting (PONV). Salamah et al.⁴⁴ found that acupressure at LI4 reduced nausea severity after laparoscopic surgery, while other studies have associated CG with decreased PONV,⁴⁵ likely through stimulation of gastric motility. The lack of statistical significance in our study may be due to limited sample size or heterogeneous risk profiles among participants.

4.3. Clinical and scientific implications

The findings underscore the clinical value of incorporating CG and LI4 acupressure into standard post-cesarean care. Given their simplicity, affordability, and non-invasive nature, these interventions are especially suited to enhance gastrointestinal recovery in diverse healthcare settings. CG, which requires no specialized training, can be seamlessly administered by nursing staff, making it highly adaptable for low-resource environments. In contrast, acupressure—though requiring trained personnel—offers the additional benefit of pain relief, and facilitating earlier mobilization. The observed trend toward reduced nausea and vomiting further suggests that both methods may support broader recovery goals and augment current antiemetic protocols.

From a scientific standpoint, this study contributes to the evolving understanding of non-pharmacological strategies in perioperative care. The comparable effectiveness of CG and acupressure, despite their distinct physiological mechanisms, highlights the multifactorial regulation of gastrointestinal function and the importance of the gut–brain axis.^27,46, 47, 48 The analgesic effect of acupressure reinforces its potential role in multimodal pain management protocols. However, given the variability in outcomes across prior studies and the non-significant findings related to PONV, further research with larger, multicenter trials is warranted. Such studies should also investigate long-term effects, optimal intervention timing, and whether combining these strategies with enhanced recovery after surgery (ERAS) protocols yields synergistic benefits.

4.4. Strengths and limitations

This study offers several notable strengths. It employed a randomized controlled design and included objective (e.g., time to first passing gas, defecation, and mobilization) and subjective (e.g., pain scores) outcomes, providing a comprehensive assessment of postoperative gastrointestinal recovery. Moreover, it adds valuable comparative data regarding two non-pharmacological, low-cost interventions—CG and LI4 acupressure—in the context of CS, a domain where empirical evidence remains limited.

Nonetheless, several limitations should be considered. As a single-center study, generalizability to other clinical settings and populations may be constrained. The nature of the interventions precluded blinding of participants and administrators, potentially introducing performance bias. While outcome assessors and data analysts were blinded, reliance on self-reported outcomes such as time to first gas or defecation introduces the risk of reporting bias. Another limitation is the lack of a placebo or sham intervention group, which limits the ability to distinguish between physiological and potential placebo effects. Although including a routine care group reflects real-world clinical conditions, it may not fully control for the expectancy effects of treatment. Additionally, the follow-up period was limited to the immediate postoperative phase, and long-term outcomes remain unknown. Despite standardization efforts, variations in individual compliance, pain thresholds, and perception of discomfort may have influenced the intervention effects.

4.5. Conclusions and directions for future research

In conclusion, this study demonstrated that both CG and LI4 acupressure, when used as adjuncts to routine post-cesarean care, significantly enhanced postoperative gastrointestinal recovery compared to routine care alone. Each intervention effectively reduced the time to first gas passage, defecation, and mobilization. Additionally, LI4 acupressure provided superior pain relief during the postoperative period. These findings highlight the potential of simple, non-pharmacological strategies to improve maternal comfort and recovery after CS.

To strengthen and expand the evidence base, future research should adopt multicenter designs involving larger, more diverse populations. The inclusion of placebo or sham-controlled groups, where feasible, would help isolate the actual physiological effects of the interventions. Extended follow-up periods are also needed to evaluate sustained benefits and long-term recovery. Additionally, further studies should explore optimal intervention timing, dosing (e.g., frequency and duration of chewing or acupressure sessions), and the potential for synergistic effects when combined with other ERAS components. Such research will contribute to refining evidence-based, patient-centered protocols for post-cesarean care. Future trials may also consider integrating patient-reported outcome measures (PROMs) and cost-effectiveness analyses to evaluate the broader impact of these interventions on quality of care.

CRediT authorship contribution statement

Hossein Bagheri: Conceptualization, Investigation, Writing – review & editing, Supervision, Funding acquisition. Seyedeh Solmaz Talebi: Formal analysis, Data curation, Writing – review & editing. Bahar Shahri: Investigation. Mobin Mottahedi: Conceptualization, Investigation, Writing – original draft, Project administration.