Validation of post‐traumatic growth inventory in mothers with the experience of having the NICU‐Hospitalized newborns “validation of post‐traumatic growth inventory”

Abstract Aims Investigating post‐traumatic growth (PTG) in mothers with the experience of having a preterm newborn hospitalized in the NICU requires a valid tool. This study aims to determine the validity and reliability of the Farsi version of the post‐traumatic growth inventory (PTGI) in mothers with the experience of having their newborns hospitalized in the NICU. Design This study was methodological research. Methods In this study, 250 mothers who had newborns with a history of NICU hospitalization during the last 3 to 12 months and had visited paediatric clinics of the selected hospitals in Tehran with the aim of having their children's condition examined were selected through convenience sampling. The data were collected using a demographic information questionnaire and PTGI. The face validity, the construct validity (confirmatory factor analysis), and the internal consistency reliability of the inventory were measured using SPSS V22 and LISREL V8.8. Results According to appropriate values for factor analysis fit indices (FI = 0.94, RMSEA = 0.07, IFI = 0.94, NFI = 0.93, RFI = 0.91, NNFI = 0.93, SRMR = 0.07), 21 items and 5 factors were confirmed for this inventory. Furthermore, Cronbach's alpha coefficient of this inventory was measured as α = 0.94. Conclusion According to favourable psychometric properties, the Farsi version of PTGI is a suitable tool for studying PTG in mothers with the experience of having preterm newborns in the NICU. Using PTGI can help nurses in planning family‐centered care interventions to reduce the impact of the mental trauma caused by the preterm newborn's hospitalization in parents. Patient or Public Contribution Mothers who had newborns with a history of NICU hospitalization during the last 3–12 months.


| INTRODUC TI ON
Preterm birth and the subsequent NICU hospitalization is a stressful and worrying experiences for parents and create a situational crisis (Aftyka, Rozalska-Walaszek, et al., 2017), while confronting the mother with traumas of separation and numerous challenges caused by the disease outcome, the treatment procedure, and care (Dhanoa & Singh, 2021).
Under these circumstances, mothers experience high levels of stress and statistically significant feelings of hopelessness, and this process overshadows the emotional and physical development of the baby and the mother-infant interaction. However, there is evidence that the process of coping with these challenges may lead to positive changes in parents. Much evidence has focused on a phenomenon called Post Traumatic Growth (PTG) in recent years (Aftyka et al., 2020;Wilson & Cook, 2018).
PTG refers to positive psychological changes that are the result of coping with great challenges and difficult life events (Tedeschi & Calhoun, 1996). In other words, positive PTG reflects the caregiver's mental ability to perform protective and regulatory functions in traumatic situations . In this regard, Boztepe et al. (2015) believe that mothers who have experienced the hospitalization of their newborns in the NICU achieve some degree of PTG (Boztepe et al., 2015). Instead of engaging in threats, horrific memories, or negative emotions caused by newborns' hospitalization, these mothers focus on providing care for the newborn  and keeping their spirits high, maintaining their resilience, and have a good performance in regard with the newborn and its needs, despite experiencing a different form of motherhood (Wilson & Cook, 2018).
According to the cognitive theory of Boztepe et al. (2015), new thoughts in those who experience a stressful incident can be the source of a positive change in them. Therefore, measuring PTG and its dimensions can help nurses as professional experts who have a close relationship with mothers use positive thoughts as a strategy for mothers to cope with stressful situations while inducing these thoughts in them, and also help them overcome the problems caused by the stressful incident to create an opportunity for growth out of the negative effects of this situation (Boztepe et al., 2015). Despite the importance of this issue, few studies are done in this field and most research focuses on a population of patients with terminal illnesses, such as cancer, and their families (Heidarzadeh et al., 2017;Morris et al., 2013). Therefore, investigating PTG in mothers who have experienced the hospitalization of their newborns in the NICU and, consequently, the need to measure this concept is an undeniable necessity.
Certain tools have been introduced to measure PTG (Tedeschi & Calhoun, 1996;Walsh et al., 2018). In 1996, Tedeschi & Calhoun developed a 21-item tool under the title Post Traumatic Growth Inventory (PTGI) to measure PTG in adults, which examines mental development in a variety of dimensions, even during the most challenging events of life (Tedeschi & Calhoun, 1996). So far, this tool has been translated into different cultures and in different languages (Aydin & Kabukçuoğlu, 2020;Pajón et al., 2020;Shirinabadi Farahani et al., 2021;Silva et al., 2018). Its validation has also been done in different countries and it has been introduced as a valid and reliable tool for many population groups (García & Wlodarczyk, 2016;Silva et al., 2018). The Farsi version of this tool has been validated by Heidarzadeh et al. (2017) in Iran, among adult patients with cancer (Heidarzadeh et al., 2017).
This study is done with the aim of determining the reliability and the validity of PTGI in the mothers with the experience of having a newborn hospitalized in the NICU and measuring their PTG, given the fact that PTG depends on the social and cultural background of the population under research (Heidarzadeh et al., 2018) and considering the positive and constructive impact of PTG on mothers' performance, helping them play their role in providing care for the newborn, and the need for a suitable tool to assess this concept and to determine the effectiveness of interventions designed and implemented for improving PTG in mothers.  (Heidarzadeh et al., 2017). This tool is scored on a 6-point Likert scale: 0 (generally none), 1 (to a very low extent), 2 (to a low extent), 3 (to a moderate extent), 4 (to a high extent) and 5 (to a very high extent). The higher the score, the higher the PTG and vice versa. In the present study, in order to evaluate the psychometric properties of the tool in the mothers with newborns hospitalized in the NICU, the face validity, the construct validity and the internal consistency were measured. For the measurement of face validity and cognitive evaluation, during face-to-face interviews, 10 mothers meeting the inclusion criteria were asked to express their opinions on the ease of use and the understandability of sentences and phrases or any possible ambiguity in the meanings of words (Keeley et al., 2013). To determine the construct validity and confirm PTGI dimensions, confirmatory factor analysis (CFA) was performed, according to which a sample size of 200 subjects was recommended based on the factors (Kline, 2015). Accordingly, and taking into account the sample drop-out, a total of 250 mothers were included in the study. CFA is a technique used to examine the fit between the hypothetical model and the data obtained from research samples. To evaluate the fit of the model, the maximum likelihood algorithm was used. There are numerous fit indices to test the appropriateness of the model and it is recommended to use several of them (Kline, 2013). To determine the internal consistency reliability, Cronbach's alpha coefficient was calculated using the data of all the participants.

| ME THODS
The present study is approved by the ethics code IR.SBMU.
PHARMACY.REC.1397.021. Before distributing the questionnaires, the researcher obtained informed consent from mothers, gave them full explanation regarding the questionnaire and assured them of the confidentiality of the data.
After being filled out, the questionnaires were collected and analysed using SPSS V22 and LISREL V8.8. The goodness of fit indices were used to confirm the dimensions, including chi-square, comparative fit index (CFI) and incremental fit index (IFI). Cronbach's alpha was also calculated to determine the internal consistency. The ordinal and categorical data and absolute and relative frequencies were calculated for the descriptive analysis of quantitative variables, mean and standard deviation.

| RE SULTS
The data were analysed using 250 questionnaires filled out by the mothers with experience of having NICU hospitalized newborns. The mean age of the mothers was 30.24 years; the mean gestational age at birth, 33.02 weeks; the mean birth weight of newborns, 1876.77 g; and clinical features can be seen in Table 1.
The results of the cognitive evaluation of the questionnaire through interviews with mothers showed that none of the expressions needed any corrections. In order to investigate the factor structure of PTGI in the mothers with the experience of having newborns hospitalized in the NICU, CFA was performed and a 5-factor model was examined. The fit indices of model are displayed in Table 2, along with the acceptable values of indices.
According to Figure  In general, according to the obtained indicators ( Table 2), it can be said that the model and its constituent concepts are acceptable and the PTGI is approved with 21 items and 5 factors in the mothers with the experience of having newborns hospitalized in the NICU.
Moreover, the internal consistency of the tool was examined and the Cronbach's alpha was calculated to be 0.94 ( Table 3).
The mean score of PTG in the mothers who had NICU hospi-

| DISCUSS ION
Although giving birth to a premature baby and its being hospitalized   Regarding the other results obtained in the present study, Cronbach's alpha coefficients for the tool and its dimensions were high, similar to the original study where the tool was developed (Tedeschi & Calhoun, 1996) and the study by Heidarzadeh et al. (2017) that has validated the tool in Iran (Heidarzadeh et al., 2017)، This indicates the consistency of the items and the stability of the dimensions. This coefficient has also been reported as acceptable in similar studies (Aftyka et al., 2020;Brelsford et al., 2020). However, in line with the present study, numerous other studies indicate that most participants have experienced less growth and changes in spiritual issues after going through a stressful situation (Byra et al., 2021;Cadell et al., 2015;Pajón et al., 2020). Because psychologically, one does a reappraisal of the situation to cope with a stressful situation, which is influenced by the level of stress, personality development, spiritual beliefs or reprioritization of important concerns in one's life which is a predictor of PTG and its dimensions (Barr, 2011).
A high level of PTG and all the positive changes and intrapersonal growth that follow depend on the type of the adopted coping strategy (Byra et al., 2021). For example, it can be said that the dimension communication with others is related to the social support perceived by parents (Li et al., 2012). One of the coping strategies that mothers adopt in the face of their child's illness is the effort to maintain emotional balance and seek appropriate support from the loved ones and relatives (Byra et al., 2021). In this regard, the results of another study show that communication among the mothers with newborns hospitalized in the NICU, their sharing of information and the emotional support they provide for each other contributes to positive orientation and further growth (Dhanoa & Singh, 2021). In other words, social interactions that are formed as a result of developing a disease or being near a patient may lead to useful changes in relationships where individuals may feel closer to others and, by gaining a better understanding of themselves and TA B L E 4 Mean score of post-traumatic growth inventory dimensions in mothers with neonatal experience in NICU.  (Dhanoa & Singh, 2021), it is recommended to conduct more studies on the other factors affecting PTG in these mothers.
One of the important limitations of this study is the time elapsed since the stressful event. Therefore, it is not clear how different mothers' experiences may be over a shorter or longer period of time.
In addition, due to the need for a high number of samples in factor analysis, the number of the samples is also considered another limitation. This fact that some complications such as low birth weight or preterm labor could possibly impact mothers' responses, generalizing these findings to mothers of neonates with a history of hospitalization in the Neonatal Intensive Care Unit should be performed carefully. Moreover, it is suggested that future studies involve a diverse population sample.

| CON CLUS ION
In general, the results of this study showed that PTGI in the mothers with the experience of having NICU hospitalized newborns has appropriate psychometric properties and can be used as a valid and reliable scale in some research protocols and in different settings among these mothers.

| RELE VAN CE TO CLINI C AL PR AC TI CE
This is because understanding positive psychological changes, identifying facilitators and using PTG dimensions to provide coping strategies can help nurses in planning and determining family-

ACK N O WLE D G E M ENTS
The authors hereby express their appreciation to all research examples, that is, the mothers with the experience of having NICU hospitalized newborns.

CO N FLI C T O F I NTE R E S T S TATE M E NT
None declared.

DATA AVA I L A B I L I T Y S TAT E M E N T
Data are the responsibility of the author. These data can be provided upon request.

E TH I C S S TATEM ENT
The present study is approved by the ethics code IR.SBMU.