Background
Childbirth pain is a unique and normal physiological phenomenon during the delivery process [1, 2]. The experience of pain during childbirth among women varies greatly. Some pregnant women feel slight pain, while some pregnant women feel intense pain, while few pregnant women experience no childbirth pain and give birth unexpectedly [3, 4]. Physiological and psychological factors of pregnant women may influence their experience of pain [5]. Nulliparous women, those who have had negative birth experiences, individuals with psychological conditions such as anxiety, and those with low birth self-efficacy endured more severe childbirth pain compared to others [3, 6, 7].
Responses to childbirth are related to cultural contexts and responses to pain may greatly vary among different cultural groups [8]. A qualitative study of West Africa found that some pregnant women express pain by crying, screaming, and shouting, while others conceal the pain, cry inside, and exhibit no outward sign of pain [9]. A qualitative study in China revealed that some pregnant women bear childbirth pain and remain stoic while giving birth because women view pain as a short, painful, but necessary step in the delivery process [10].
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Childbirth pain is considered one of the most severe pain they will ever experience by humans [1, 2]. Several studies have shown that most pregnant women actually experience a higher degree of pain during childbirth than they expected. Unexpected pain and pain-induced fear have many adverse effects on the psychological and physiological states of the mothers and their babies [11, 12]. Persistent pain during childbirth may raise the risk of fear of childbirth and post-partum depression, contributing to the development of post-traumatic stress disorder. The unpleasant experience of childbirth due to severe childbirth pain has led to an increase in the rate of assisted delivery and caesarean section, which is also associated with a decrease in the willingness to become pregnant in the future [13, 14]. In addition, severe childbirth pain may also lead to prolonged labour, affecting the safety of mothers and their babies [15].
Childbirth pain management methods include both pharmacologic and non-pharmacologic options [16]. The non-pharmacological options could help pregnant women cope with childbirth pain, whereas the pharmacological options is a way to relieve the pain of childbirth [17]. Pharmacologic options include inhaled analgesia, opioids, non-opioid drugs, local anaesthetic nerve blocks, and epidural (including combined spinal epidural). The pharmacological options could relieve pain quickly, but it may increase adverse reactions, such as nausea, drowsiness, hypoventilation, low blood pressure, motor blocks, fever, etc., and increase the risk of prolonged labour, assisted delivery, caesarean section, and fetal hypoxia [18]. Non-pharmacological options include hypnosis, biofeedback, intracutaneous or subcutaneous sterile water injection, immersion in water, aromatherapy, relaxation techniques (yoga, music, audio), acupuncture or acupressure, and transcutaneous electrical nerve stimulation (TENS). The non-pharmacologic options may be safer but less effective for pregnant women and newborns than pharmacologic options [3].
Assessment of childbirth pain is the first step in childbirth pain intervention. The study found that the assessment of pain is strongly idiosyncratic and differences in pain assessment methods affect the individual responses to pain [19]. Moreover, the subjective assessment of pain was differentially associated with the objective assessment of pain [20]. Because of the complex subjective nature of pain, the measurement of pain, and the measurement of childbirth pain in particular is more challenging and specific than other vital sign measurements [4]. Currently commonly used methods of childbirth pain assessment include visual analog scale (VAS), numeric rating scale (NRS), verbal rating scale (VRS), etc. These methods require the clinicians and midwives to explain the process of pain assessment to the pregnant woman and then the woman, who then gives her own pain score. These require that both the healthcare providers and the pregnant woman speak the same language [21]. However, pregnant women have expressed a desire not to be disturbed during birth, and some refuse to have too many interviews during the second stage of labour [22]. At the same time, the current philosophy of care during childbirth and delivery is to minimize excessive interventions at the time of birth [23]. In addition, the number of pregnant women who are unable to communicate effectively with healthcare providers has increased as a result of changes in social processes and an increase in human migration [24]. The foregoing makes it more critical to design a scientific, effective, and objective auxiliary assessment instrument for childbirth pain. This instrument could help healthcare providers objectively assess childbirth pain based on the midwife’s observation without interfering in the birthing process and cultural limitations.
Rating Scale of Pain Expression during Childbirth (ESVADOPA) which was constructed based on the Campbell scale, is an assessment instrument that could evaluate childbirth pain and was developed by Silvia Navarro-Prado in 2019 [24]. The Campbell scale assesses pain in patients who are unable to communicate spontaneously by scoring five aspects including face, restlessness, muscle tone, vocalization, and consolability [25]. Thus, the scale could quickly assess the level of childbirth pain of pregnant women through the assessment of facial muscles, body response, verbal response, restlessness, ability to relax, and vegetative symptoms without interrupting or interviewing the pregnant woman in labour. Due to specific cultural differences between China and other countries, the expression of pain in pregnant women also has specific differences. Whether this scale could be used as an auxiliary assessment instrument to evaluate childbirth pain in Chinese pregnant women needs to be rigorously checked on the psychometric properties. Therefore, the purpose of this study was to translate, cross-culturally adapt and validate the ESVADOPA in a sample of Chinese pregnant women.
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Methods
Design
The cross-sectional and methodological study was performed at Shandong Provincial Hospital Affiliated to Shandong First Medical University between June 2021 and June 2022.
Participants
The inclusion criteria of pregnant women were as follows: (1) ASA I or II; (2) in the first stage of labour (①Regular painful contractions: contractions are increasing in length and intensity and are coming at decreasing intervals; ②Cervical effacement and dilatation; ③fetal head descent); (3) age⩾18 years old; (4) gestational age⩾37 weeks; (5) have no contraindications for vaginal birth; (6) have the willingness to participate in the study. The exclusion criteria of pregnant women were as follows: (1) caesarean section; (2) pharmacological interventions of pain management before the evaluation; (3) have no willingness to participate in this study.
Instruments
Rating scale of pain expression during childbirth (ESVADOPA)
The ESVADOPA, which consists of 6 items including facial muscles, body response, verbal response, restlessness, ability to relax, and vegetative symptoms, was developed in 2020. Each of the items scored from 0 to 3, with 0 meaning an absence of pain expression and 3 meaning a maximum pain expression. The total score is ranging from 0 to 18. The higher the score, the higher the degree of pain. No express pain, mild pain, moderate pain, and intense pain are < 1, 1–6, 7–12, and 13–18, respectively [24].
Questionnaire with social-demographic characteristics
The socio-demographic characteristics of pregnant women were their age, gestational week, parity, education, pregnancy complications and so on.
Numeric rating scale (NRS)
The NRS is an 11-point numeric scale in which patients select a whole number (0–10) to describe the intensity of pain. A larger number indicates greater pain intensity. Among them, 0 = no pain, 1–3 = mild pain, 4–6 = moderate pain, 7–9 = severe pain, and 10 = worst pain imaginable. NRS is a numbered version of VAS that can measure the pain intensity of patients with different diseases and characteristics [26]. Both VAS and NRS are the preferred pain assessment scales in clinical practice due to thire simplicity and ease of completion [27]. Compared to VAS, NRS is the first choice for scientific research due to comprehensibility and precise written management [28].
Procedures
After getting the permission of Silvia Navarro Prado to use ESVADOPA, we translated and cross-culturally adapted the scale from English to Chinese based on Brislin’s classical back translation model [29].
Translation procedure
A total of 4 translators participated in this study, including 3 translators whose official language is Chinese and 1 translator whose first language is English. Translator 1: A bilingual translator with a master’s degree, who is familiar with the development process of scale, and is able to translate the scale from English to Chinese. Translator 2: A bilingual translator with a Ph.D. degree who is familiar with pain management during childbirth. Translator 3: A bilingual translator with a master’s degree and English cultural background who has experience in the translation of scales and clinical experience in obstetrics. Translator 4: Master’s degree translator is familiar with pain management during childbirth with English as the official language.
Step 1: Translator 1 and Translator 2 translated the scale from the source language to the target language to form the Chinese version of scale ① and ②. They compared and discussed the differences between the two translated scales to create the Chinese version of ESVADOPA I. Step 2: Translator 3 who had no knowledge of the original version, translated the Chinese version of ESVADOPAI into the English version, of ESVADOPAII. Step 3: Translator 4 compared and analyzed ESVADOPAII with the original version of the ESVADOPA according to English idiomatic expression. When there were differences between the two versions of the scale, translator 4 explained the differences to translators 1, 2, and 3. Translators 1, 2, 3 and 4 jointly discussed and formed the back-translated English versions of the ESVADOPA III. Step 4: Translators 1, 2 and 3 jointly discussed and translated the back-translated English versions of the ESVADOPA III into Chinese version of ESVADOPA III.
After group discussion, the researchers cross-culturally adapted the items to make them readable and understandable according to the cultural background of China. Midwives and pregnant women who met the inclusion and exclusion criteria were randomly selected for the first round of pre-experiment. 18 midwives were chosen to evaluate the pain expression during childbirth of 30 pregnant women using ESVADOPA IV for pre-experiment. All midwives were female, with (10.333 ± 5.811) of working experience years and in the age of (32.333 ± 4.899) years. In terms of education level, 3 midwives have College degrees, 13 midwives have Bachelor degrees and 2 midwives have Master degrees. The average age was (28.033 ± 3.157) years old and the average gestational age was (275.833 ± 4.728) days of the pregnant woman. After the first round of pre-experiment, the statement of the items was modified according to the feedback results of midwives, and ESVADOPA V was formed. The statement of the first item was changed from “Relaxed with slight facial tightening during most of the contraction” to “Slight tension in the face during contraction”. The statement of the fourth item was changed from “Calm, relaxed, normal movements during the entire contraction” to “Keep relaxed and carry out daily activities throughout the contraction”.
15 midwives were randomly selected to evaluate the pain expression during childbirth of 20 pregnant women using ESVADOPA V for the second round of pre-experiment. All midwives were female, with (10.750 ± 6.050) years of working experience and in the age of (32.750 ± 5.053) years. In terms of education level, 2 midwives have College degrees, 10 midwives have Bachelor degrees and 3 midwives have Master degrees. The average age was (27.600 ± 3.362) years old, and the average gestational age was (276.650 ± 6.098) days of the pregnant woman. After the second round of pre-experiment, all midwives reported no misunderstanding of scale and items, at this point, the final Chinese version of the ESVADOPA was completed.
We cooperated closely with the original author and sent the Chinese version, the original version, and the English translation of the Chinese version of the scale to the original author to guarantee the equivalence between the content of the Chinese version of ESVADOPA and the ESVADOPA in the process of cross-cultural adaptation.
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Data collection procedure
Pregnant women were recruited and invited to participate in the study by convenient sampling. In the delivery room, content and methods, standardized explanations of the research objectives, research procedures were given to the pregnant women to ensure their complete understanding. Then, the pregnant women who agreed to participate in the study signed the online or paper informed consent. Pregnant women communicated with researchers and made choices according to their preferences when the pregnant women were calm and without contractions.
Data were collected while the women were in the first stage of labour. The researchers conducted a vaginal examination according to the evaluation of the stage of labour and the willingness of pregnant women. Then, the midwife explained to the pregnant woman how to use the Numeric Rating Scale (NRS) to assess childbirth pain by herself. The pregnant woman assessed the pain rating using the NRS by herself while the midwife completed the Rating Scale of Pain Expression during Childbirth (ESVADOPA) at the next contraction. If the midwife doubts the results of scale, she can re-evaluate two consecutive contractions. However, the evaluation by the midwife and pregnant woman had to be performed based on the same contraction. The vaginal examination was conducted by the midwife who completed the ESVADOPA.
After the delivery of the newborn, questionnaires were reviewed based on inclusion and exclusion criteria by researchers. One hour after delivery, the researchers explained the content of the survey to the pregnant women and asked them about their willingness to participate in the study again. If the pregnant women refuse to continue participating in the study, the researchers will express gratitude and delete the privacy of pregnant women. If the pregnant women agree to continue participating in the study, the researchers will fill out the questionnaire with socio-demographic characteristics according to the health care cards and medical records of pregnant women. Data were collected in two separate sessions by selecting from the provincial general hospital in China, with predefined methods and inclusion and exclusion criteria. Sample 1 was applied for item statistical analysis, reliability, and EFA of the ESVADOPA. Sample 2 was used to assess the scale’s degree of data fitting.
Data analysis
SPSS 23.0 and AMOS 23.0 were used to analyze the data. The social-demographic characteristics and scale scores were analyzed using descriptive statistics. Data were represented by means (± SDs) or frequencies (with percentages). P < 0.05 indicated statistical significance.
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Item statistical analysis
Item distribution method, critical ratio (CR) analysis method, and correlation coefficient method were used for item statistical analysis of the scale. (1) Item distribution method: If the selection rate of each option for an item accounted for more than 80%, the item was considered for deletion. (2) Critical ratio (CR) analysis method: The two groups (top 27% and bottom 27% based on the total score of the scale) were tested by an independent-samples t-test. Items were deleted when P > 0.05. (3) correlation coefficient method: Pearson`s correlation coefficient was used to evaluate the score of each item and the total scale. Items with a low coefficient (< 0.2) and/or a high P value (> 0.05) were considered for deletion.
Reliability
Cronbach’s α coefficient, the McDonald Omega and split-half reliability were used for reliability analysis of the scale. If the Cronbach’s α coefficient, the McDonald Omega and split-half reliability of scale ≥ 0.07, the reliability analysis of the scale was considered acceptable.
Validity
Content validity
The content validity of the study was evaluated using the scale-level content validity index (S-CVI) and item-level content validity index (I-CVI). A panel of six experts in childbirth pain management assessed the scale’s relevance, correctness, and comprehensibility of the scale, using the following 4-point scale: 1 = “not at all”, 2= “somewhat”, 3 = “moderately so”, and 4 = “very much so”.
Structure validity
Exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and criterion-related validity were used for validity analysis of the scale. Kaiser-Meyer-Olkin (KMO) test and Bartlett’s test of sphericity were used for sample 1 and 2 to determine whether or not EFA and CFA could be performed. Sample 1 was randomly selected for EFA to analyze the factor structure of the scale. Principal axis factoring (PAF) and factor rotation were used to perform the EFA while inspecting the results of the eigenvalue and scree plot. Composition of sample 2 with remaining data for CFA to verify the fitting degree of the model. In CFA, square root mean residual (RMR), root-mean-square error of approximation (RMSEA), goodness-of-fit index (GFI), adjusted goodness-of-fit index (AGFI), comparative fit index (CFI), and other results of fit Indexs should meet the criteria. Pearson’s correlation coefficient between NRS pain score and ESVADOPA was used to evaluate the criterion-related validity.
Criterion-related validity
There was explored the relation between ESVADOPA and NRS pain score was used to determine the criterion-related validity of ESVADOPA. Pearson’s correlation coefficient between NRS pain score and ESVADOPA was used to evaluate the criterion-related validity.
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Ethical considerations
This study obtained approval from the Ethics Committee of Shandong Provincial Hospital Affiliated to Shandong First Medical University (SWYX: NO.2022 − 110). Informed consent was understood and signed by the all participants and their privacy was kept strictly confidential. All methods and procedures were carried out in accordance with the Declaration of Helsinki ethical guidelines.
Results
Social-demographic characteristics of pregnant women
500 pregnant women were enrolled and 487 valid questionnaires were completed, the participant rate was 97.4%. Sample 1 consisted of 257 pregnant women, and sample 2 consisted of 230 pregnant women. The average age was (29.96 ± 3.864) years old, and the average gestational age was (276.05 ± 7.940) days. There were no significant differences in demographic characteristics between samples 1and 2.
Item analysis
The range of all items’ options from 0 to 4 was 4.67%~30.74%, 37.35%~64.59%, 7.78%~46.69%, and 2.72%~11.28%, respectively. The distribution of all items’ options was less than 80%. The correlation coefficient between the items and the ESVADOPA score was between 0.654 and 0.819 and had statistical significance (P<0.05) (see Table 1).
Table 1
Item statistics results of the ESVADOPA (6 items, n = 257)
Item | Distribution of items’ options | critical ration t | correlation coefficient | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
0 | Percent (%) | 1 | Percent (%) | 2 | Percent (%) | 3 | Percent (%) | |||
1 | 12 | 4.67 | 96 | 37.35 | 120 | 46.69 | 29 | 11.28 | 15.780** | 0.781** |
2 | 22 | 8.56 | 100 | 38.91 | 117 | 45.53 | 18 | 7.00 | 17.159** | 0.798** |
3 | 62 | 24.12 | 107 | 41.63 | 72 | 28.02 | 16 | 6.23 | 18.339** | 0.819** |
4 | 39 | 15.18 | 116 | 45.14 | 91 | 35.41 | 11 | 4.28 | 15.789** | 0.796** |
5 | 39 | 15.18 | 166 | 64.59 | 45 | 17.51 | 7 | 2.72 | 13.700** | 0.822** |
6 | 79 | 30.74 | 145 | 56.42 | 20 | 7.78 | 13 | 5.06 | 10.544** | 0.654** |
Validity
Content validity
The S-CVI was 0.958 (> 0.78), and the I-CVI was ranging from 0.875 to 1.000 (> 0.78). The result showed that the scale has content validity, so no items were deleted.
Factor structure
The results of the KMO coefficient (0.895) and Bartlett’s test of sphericity (χ2 = 674.455, P < 0.001) indicated that the samples in this study were suitable for EFA. The Scree plot showed a curve that levelled off at factor number 1 with corresponding eigenvalue > 1. One factor was identified and explained 61.064% of the total variance. Factor 1 contained 6 items with factor loadings between 0.626 and 0.839 (see Table 2; Fig. 1).
Table 2
Factor structure for ESVADOPA (n = 257)
Item | Factor 1 |
|---|---|
1 | 0.786 |
2 | 0.807 |
3 | 0.812 |
4 | 0.798 |
5 | 0.839 |
6 | 0.626 |
Fig. 1
Scree plot showing cut-off point for scale factors (n = 257)
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Confirmatory factor analysis
The one-factor model identified in the factor structure was tested in sample 2 using confirmatory factor analysis to determine validity and appropriateness. Confirmatory factor analysis showed that the one-factor structure of the ESVADOPA fit the data well (χ2 = 15.859, df = 9, χ2/df = 1.762, GFI = 0.976, CFI = 0.990, RFI = 0.961, NFI = 0.977, AGFI = 0.945), and align with the expected study results. And RMSEA (RMSEA = 0.039) is also aligned with the expectation, which is considered worthier as an appropriate index (see Table 3; Fig. 2).
Table 3
Appropriate indices of model for ESVADOPA (n = 230)
Absolute fit indexs | Result | Incremental fit indexs | Result | Simplicial fit indexs | Result |
|---|---|---|---|---|---|
χ2 | 15.859 | NFI | 0.977 | χ2/df | 1.762 |
RMR | 0.015 | RFI | 0.961 | PGFI | 0.418 |
RMSEA | 0.058 | IFI | 0.990 | PNFI | 0.586 |
GFI | 0.976 | TLI | 0.983 | PCFI | 0.594 |
AGFI | 0.945 | CFI | 0.990 | CN | 313 |
Fig. 2
CFA standardised item loadings and factor correlations for ESVADOPA (n = 230; p < 0.001)
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Criterion-related validity
The results showed that the ESVADOPA were significantly and positively correlated with NRS pain score (r = 0.729, P<0.001).
Reliability
The Cronbach’s α coefficient for the ESVADOPA was 0.868. The McDonald Omega was 0.896. The Spearman-Brown split-half reliability of the scale was 0.845, Guttman split-half reliability was 0.842. These results showed that the reliability of ESVADOPA was overall good.
Discussion
This study translated and cross-culturally adapted the ESVADOPA, and validated the psychological properties of the scale in a sample of Chinese pregnant women. The results of the study showed that the scale achieved satisfactory reliability and validity, and can be used as an auxiliary assessment instrument to evaluate expression, level, and changes of pain in Chinese pregnant women during childbirth.
Our team translated and cross-culturally adapted the scale, which is the first step in the introduction of the scale. This step could facilitate the deep integration of the scale with the Chinese cultural background and ensure that the Chinese users of this scale have the same understanding of the scale items and meanings. Brislin’s classical back translation model was strictly applied to translate and cross-culturally adapt the scale throughout the study process. Then, we applied the scale to a sample of 487 Chinese pregnant women. The results of the EFA showed that the scale had one factor and contained 6 items. The reliability and validity of the ESVADOPA meet the criteria for psychological instrument development, indicating that the ESVADOPA can be considered an excellent objective assessment instrument.
The study found that pain measurement methods affect the interpretation of individual responses to pain [19]. When using subjective pain measurement instruments such as NRS, healthcare providers usually ask the mother if she is experiencing pain. Negative words such as pain could cause people to focus on the pain itself and associate it with normal sensations in a negative way, increasing the level of pain and anxiety [30, 31]. Neutral or more positive words, such as comfort, could alleviate perception and experience of pain. In addition, due to some cultural beliefs, pregnant women remain silent during contractions, which affects healthcare providers to use subjective measurement instruments to evaluate childbirth pain and take appropriate pain intervention methods [32]. However, when pregnant women are exposed to severe pain and fear, the hormonal release, such as cortisol, catecholamines, and β-endorphins, is abnormal, which causes the autonomic nerves and muscles of the body to react beyond their control [33]. Healthcare providers could use objective pain assessment instruments to assess pain by observing the body response, which can effectively supplement the shortcomings of some subjective measurement instruments of pain [4]. ESVADOPA could quickly and objectively evaluate childbirth pain during contractions and childbirth by observing facial muscle Response, body response, verbal response, restlessness, relaxation ability, and autonomic symptoms. For some patients who are unable to accurately express their feelings, such as some hearing-impaired patients, this scale could help healthcare providers to analyze their pain more quickly and comprehensively than other instruments through their performance and response while asking about their feelings.
This study is the first time that ESVADOPA is being translated and cross-culturally adapted and validated in another language. Compared to the original scale, the Chinese scale has the same items but different dimensions. The items of the Chinese version matched the original items, with no items being deleted. While the original ESVADOPA demonstrated two factors in factor analysis conducted with pregnant women populations, the Chinese version revealed a one-factor construct. These results can be attributed to several justifications. Firstly, differences in the expression of childbirth pain in pregnant women between domestic and international contexts may stem from variations in social backgrounds and cultural groups [34]. Secondly, the original structure was affected by translation and cross-cultural adaptation [35].
This study also had several limitations. Firstly, this study had certain sample selection limitations. Participants of this study came from only one provincial general hospital which may not be representative of all Chinese pregnant women. Therefore, future research is needed to evaluate pregnant women in different hospitals and provinces in China to confirm the stability of the structure of the ESVADOPA. Secondly, the scale should be assessed by midwives according to the expression and performance of pain in pregnant women. This scale is an objective assessment instrument, and the accuracy of the results is influenced by the midwife’s understanding of the scale items and meanings. Thus, midwives from different hospitals and provinces should be invited to participate in future research to ensure that most midwives have a consistent understanding of the scale items and meanings.
Conclusions
The primary issue with scientific pain management lies in effectively assessing pain. This study introduced and evaluated the reliability and validity of ESVADOPA to provide a new instrument for assessing the pain rating of pregnant women during childbirth and improving childbirth pain management. The Chinese version of ESVADOPA includes 6 items, which have been confirmed to have sufficient reliability and validity in Chinese pregnant women samples. The scale could be used as an auxiliary assessment instrument to meet the requirement for clinical and scientific research to evaluate the pain of childbirth in pregnant women. With the change in the concept of childbirth pain management and the emphasis on maternal labour safety, the scale could help clinicians and midwives to evaluate the pain rating during childbirth more comprehensively.
Acknowledgements
The authors would like to express their thanks to all the women and midwives who participated in this research enabling this study to be conducted.
Declarations
Ethics approval and consent to participate
This study obtained the approval from the Ethics Committee of Shandong Provincial Hospital Affiliated to Shandong First Medical University (SWYX: NO.2022 − 110). All participants understood and signed the informed consent and their privacy was kept strictly confidential. All methods and procedures were carried out in accordance with the Declaration of Helsinki ethical guidelines.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
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