Longitudinal Changes in Parenting Stress of Mothers of Children with Cerebral Palsy and Children’s Gross Motor Function System Level

Abstract

Background: Stress caused by children with disabilities harms the growth and development of children and their families. The present study aimed to investigate whether parenting stress of mothers of children with cerebral palsy changes and the relationship between gross motor function level and changes in parenting stress.

Methods: Data on 162 children with cerebral palsy were collected over a 2-year period and measured thrice. Gross motor function and parenting stress were assessed using the Gross Motor Function Classification System and the Korean version of the Parenting Stress Index Short Form. Latent growth curve models of linear, Wave 2, and Wave 3 variation in parenting stress were constructed. The relationship between the Gross Motor Function Classification System level and parenting stress was evaluated via latent growth modeling. 

Results: The linear variation models reflected the time evolution of parenting stress. There were individual differences in parenting stress at the initial level and no individual differences in the change of parenting stress. The relation between initial level and change rate of parenting stress was not significant. Higher initial values of Gross Motor Function Classification System level were associated with higher initial values of parenting stress, but not related to a change of parenting stress.

Conclusions: The results showed that parenting stress of mothers with children with cerebral palsy was decreasing over time and that Gross Motor Function Classification System level was related to parenting stress level. Based on these findings, a proposal for a further research is put forth.

Background

Parents experience various stressors while performing their parenting roles, collectively referred to as parenting stress (1). Numerous studies have demonstrated that the parenting stress of mothers caring for children with disabilities is higher than that of mothers caring for children with normal development (2–4). Factors that increase parenting stress include the age of the child (5), the degree of disability (6, 7), and problem behavior of children (8) were identified. Factors that decrease parenting stress include social support (9, 10), social network (11), and coping strategy (12).

Continuous parenting stress is highly likely to cause depressive symptoms due to an increase in negative emotions such as anxiety, nervousness, and feelings of inferiority and a decrease in confidence in parenting (13–15). In addition, parenting stress is a factor that hinders child development by negatively affecting parental interactions with children (16). When mothers treat their children affectionately and acceptably and control their emotions, children develop high social skills (17). The more stress a mother perceives, the more coercive and rejecting parenting behavior she will display toward her child. In response, the child's self-esteem is lowered (18) and anxiety and depression can develop (19), which impairs social skill acquisition (1).

In research on parents of children with cerebral palsy (CP), findings generally indicate that levels of parenting stress are higher than those of parents with able-bodied children (20). Although it is not clear why some parents have low stress and others have high stress, a recent review of factors involved in the adaptive process has investigated many child- and parent-related factors, and various sources of contextual support (21). Studies on disabilities among children that affect parenting stress have continued to be published, and reported influences of disability or gross functional level of children with CP differ in degree. Specifically, gross function level was reported to be a variable contributing significantly to elevated parenting stress (22), while other findings indicated that the degree of motor function impairment did not correlate with parenting stress (7).

Boss (23) described parenting stress as the tension and pressure within the family system that individuals and families inevitably experience in the process of development and change over time, and the degree of difficulty or burden perceived by parents due to child rearing. As such, studies on parenting stress and children's development show that parenting stress is not a temporary phenomenon, but one that is continuously experienced throughout the child-rearing process, with long-term effects on parental depression and child development. Crnic, Gaze (16) revealed that mothers' parenting stress is a constant characteristic that does not change significantly, and a major variable that can directly or indirectly affect maladjustment during infant growth.

There is a need for empirical investigation into the changes in parenting stress in mothers of children with (CP), the variables that affect the pattern of such changes, and the role they play according to the passage of time. Until now, a cross-sectional approach to parenting stress in mothers of children with CP has yet to be attempted, and longitudinal studies focusing on the pattern of change or influencing factors are rare. Therefore, this study intended to analyze the changes in parenting stress in mothers of children with CP over time and how children's gross motor function level affects the changes using a longitudinal approach.

The research questions for this study are as follows. First, does the parenting stress in mothers of children with CP change? Second, does the level of gross motor function in children with CP affect the changes in a mother's parenting stress?

Methods

Participants

Participants in this study comprised 162 children with CP receiving rehabilitation treatment at a hospital or community welfare center or attending a school for physical disabilities, and their mothers. Sampling was done across the country, except Jeju Island. The criteria for selection of participants were 1) children with a medical CP diagnosis 2) mothers of children ranging from 3 to 18 years old 3) mothers who responded three times during the two-year study period. The study was approved by the Research Ethics Board of the Jeonju University on 14 November 2013(ethical approval code number: Jeonju University IRB-1041042-2013-1). The mean age of children with CP was 9.6 years (SD = 4.69). The general characteristics of participants are shown in Table 1.

Measure

Gross Motor Function Classification System (GMFCS)

GMFCS was used to evaluate the gross motor function of children with CP. Children's motor skills are assessed on a basis of five levels, with level 1 being able to walk without any restrictions, level 2 being able to walk with restrictions, and level 3 being able to walk without trunk support using canes, crutches, or walkers. Level 4 indicates that a child’s walking is limited but they are able to move independently using an electric wheelchair or other means of transportation, and level 5 indicates that mobility is severely limited even with assistive devices (24). Park (25) reported that the coefficients ranged from 0.690 to 0.789 and the GMFCS remained stable in children with CP aged 2 to 12 years. 

Parenting Stress Index

The Korean Parent Stress Index Short Form (K PSI-SF) was used to evaluate the mothers’ parenting stress. The K PSI-SF is a tool for the identification and diagnosis of parenting-related stress, and it is designed to measure the relative stress level in a parent-child relationship. It can be used by parents of children over one month old. It consists of three domains including parent distress, parent-child dysfunctional interaction, and difficult child characteristics. The validity and reliability of K-PSI-SF was confirmed through Rasch analysis, and the internal consistency of the entire test was reported to be .92 (26).

Procedure

To investigate changes in the parenting stress of mothers raising children with CP, 162 children according to the selection criteria were sampled and data were collected in the first year. This study was approved by the Jeonju University Research Ethics Committee (Jeonju University IRB-1041042-2013-1). In Wave 1, data on the GMFCS level and parenting stress were investigated, and in Wave 2 and 3, only data on parenting stress were investigated. The level of GMFCS was evaluated by a physical therapist who had treated the child for more than six months. Participants in Wave 1 also participated in Wave 2 and 3. The mothers responded to the K-PSI-SF. After the third evaluation, it was investigated whether changes in parenting stress and the level of GMFCS in Wave 1 affected the changes in parenting stress in subsequent years through the latent growth curve model.

Statistical Analysis

A latent growth model was applied to find out how the parenting stress of mothers of children with CP changed for each participant over time. Covariance structure analysis was used to apply and analyze the latent growth curve modeling to actual data, which necessitated a sample size of at least 150 (27). The participants of this study comprised 162 children and adolescents with CP receiving rehabilitation treatment at hospitals or community welfare centers, which met the sample size for the analysis of the latent growth curve modeling.

The basic linear change model, the change model in Wave 2, and the change model in Wave 3 were first verified using the parenting stress evaluation data from the first to the third years. The suitability of the linear change in parenting stress was confirmed by comparing the fitness indices of the change models. In this study, the comparative fit index (CFI), the non-normalized fit index (NNFI or Tucker-Lewis Index: TLI), and the standard fit index (NFI), which are relative fitness indices, were used as an index. If fit indices are above .90, the model is considered to have good fit (28). Root mean square error of approximation (RMSEA) values 06–0.08 indicate reasonable. Researchers estimating models from data do not trust χ² because the power of the χ² test lacks (29). Therefore, the χ2 test was not used for fitness indices in this study.

After confirming the change model of parenting stress, the relationship between the change trajectory of parenting stress and the GMFCS level was investigated through multivariate latent growth modeling. For descriptive statistical analysis such as mean, standard deviation, correlation, SPSS 26.0 was used; for latent growth modeling analysis, AMOS 26.0 was used.

Results

Descriptive statistics 

The mean parenting stress was 97.58 (SD = 19.03) in the first year, 94.19 (SD = 18.03) in the second year, and 93.87 (SD = 18.34) in the third year (Table 2). The intercorrelations among study variables are presented in Table 3. The GMFCS level and parenting stress in the first year was significantly correlated (p < 0.05).

Analysis of change in parenting stress and the GMFCS level

Results regarding the models’ quality of fit are presented in Table 4. Upon comprehensive examination of the value of χ², RMSEA, CFI, and TLI, it was observed that the linear change model was the best fit for analyzing parenting stress. 

Table 5 shows the changes in parenting stress based on the linear change model. The initial value for parenting stress was shown to be on average 95.883 (p < 0.001) with variance of 209.505 (p < 0.001), and the rate of change was on average -2.552 (p < 0.05) with variance of -14.908. The mean and variance of the initial values were significant, indicating that individual differences exist in parenting stress. The average of the significant rate of change means that parenting stress changed significantly over two years, and the non-significant variance means that the trajectory of change over two years of parenting stress has no significant individual difference in children with CP. The significance of the covariate reflects the relationship between the initial value and the rate of change. In the case of parenting stress, the covariate was not statistically significant.

The relationship between evolution of parenting stress and GMFCS level

The results regarding the relationship between the evolution of parenting stress and GMFCS level are presented on Table 6 and Figure 1.

The suitability of the model was verified as the value of χ2 was found to be 18.186 (degree of freedom = 10), and the values of NFI, CFI, TLI, and RMSEA were 0.914, 0.910, 0.957, and 0.071, respectively. Results showed that the higher the initial values of GMFCS level, the higher the initial values of parenting stress (B = 1.994, p < 0.05). 

Discussion

Mothers’ parenting stress occurs during the performance of parenting roles in family life and the developmental process faced by the family system (30). Previous studies on mothers’ parenting stress have reported that this stress changes over time (31, 32), but studies on such changes in mothers of children with CP are lacking. Parenting stress weakens mothers' interest in child rearing, leading to dysfunctional parenting behavior (33). Therefore, this study was conducted to investigate the changing parenting stress of mothers of children with CP and the relation between GMFCS level and these changes. The focus was to provide recommendations for practices and future research in addressing major findings. 

First, it was confirmed that the parenting stress of mothers of children with CP decreased over time. To confirm the change tendency of parenting stress, the linear, first-year, and second-year change models were set as competition models and analyzed through the latent growth model. It became evident that the linear change model best fit the analysis of parenting stress, indicating that parenting stress changes over time in mothers of children with CP. The average change rate was negatively significant, indicating that parenting stress decreased linearly over time. The initial value of the parenting stress variable and the variance of the initial value were found to be statistically significant, which means there are individual differences in the level of parenting stress at each time point. The rate of change was significant and the variance of the rate of change was not significant, indicating that parenting stress decreased significantly over time and there was no difference between individuals. 

Previous studies report that parenting stress for infancy children increases and decreases with certain age. Mulsow, Caldera (30) measured changes in parenting stress for 164 mothers and infants and reported that the mothers' parenting stress increased then decreased between two and three years of age. Williford, Calkins (31) measured changes in parenting stress between the ages of two and five for 430 mothers of children and reported that the mothers' parenting stress decreased after two years of age. The results of a longitudinal study of parenting stress for low-income white mothers conducted by Chang and Fine (34) showed that the child's age gradually decreased with increasing age. The pattern of parenting stress reduction in mothers of children with CP is consistent with the results of studies showing that parenting stress is reduced following infancy. This is likely because the children of this study were three years of age or older. Therefore, in future research, it is necessary to conduct a study on the changing patterns of parenting stress for mothers of children with CP in infancy.

Despite high stress levels, not all caregivers of children with disabilities have difficulties adjusting (5). While some families have difficulty managing the circumstances associated with the child-rearing process of a child with a disability, some families are successful in adjusting (35). In studying human adaptation, instead of focusing on the negative effects of life adversity on humans or vulnerabilities that are prone to negative states, the strengths of the subjects and their tendency to change perspectives in the direction of strengthening one's resources are recognized (36). Adaptive flexibility or resilience is a concept that best expresses the ability to successfully recover by reducing negative impacts and lead to positive changes such as growth in spite of crises and stressors that are inevitably encountered in life (37). Until now, studies on parenting stress for parents of children with disabilities have had limitations that show the parenting stress of caregivers of children with disabilities is higher than that of caregivers of general children (2, 3). Therefore, in future studies, it is necessary to study the factors affecting the reduction of mothers' parenting stress for children with CP. 

Second, it was found that the level of gross motor function of children with CP had a significant effect on the initial value of mother's parenting stress. The functional level of children with CP has been regarded as a major factor influencing parenting stress (22). Studies on the influence of the degree of disability or functional level of children with CP have uncovered different findings, but most studies agree that the more severe the disability of children with CP, the higher the parental stress (22, 38). However, there is a difference from the results of this study, in that previous studies reported a high correlation between functional level and parenting stress according to the results of a cross-sectional study. The results of this study showed that the GMFCS level of children with CP had an effect on the initial value of parenting stress, but did not affect the change rate. These results are probably related to the stability of GMFCS levels in children with CP. Stability of GMFCS levels in children with CP has already been reported (39, 40). The results of this study, which showed that parenting stress decreased over time in mothers of children with CP, suggests that it is necessary to investigate the factors that may affect the reduction of parenting stress.

Conclusion

Longitudinal studies on children with CP have mainly focused on the children themselves, such as changes in the level of gross motor function of children with CP, changes in their quality of life, and the relationship between the level of gross motor function coordination and ability to perform activities of daily living. These studies account for the majority, while studies on families of children with CP are difficult to find. This study is significant in that it reported the results of longitudinal changes in parenting stress in mothers. Through this study, it was confirmed that the parenting stress of mothers of children with CP showed a decreasing trend over time. In addition, it was confirmed that the gross motor function level of children with CP affected the initial level of parenting stress but did not affect the change.

Abbreviations

CFI, Comparative fit index 

CP, cerebral palsy 

GMFCS, Gross Motor Function Classification System

K PSI-SF, Korean Parent Stress Index Short Form

NFI, Normed fit index

RMSEA, Root mean square error of approximation

TLI, Tucker-Lewis-Index

Declarations

Ethics Approval and Consent to Participate

The Jeonju University Institutional Review Board approved this study (IRB no. 1041042−2013−1). Mothers of children with CP agreed to the purpose and procedures of this study and provided written informed consent to participate. All methods were carried out in accordance with relevant guidelines and regulations.

Consent for Publication

Not applicable. 

Authors’ Contributions

EY analyzed and interpreted the data. EY was a major contributor in writing the manuscript.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding

This research received no external funding.

Acknowledgments

I would like to thank the mothers of children with cerebral palsy for agreeing to participate in this study. 

Data Availability Statement

The data available from the corresponding author on reasonable request

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Tables

Table 1. Characteristics of participants

Notes. GMFCS = Gross Motor Function Classification System.

Table 2. Descriptive statistics of parenting stress

Table 3. Correlation between variables

Note: GMFCS = Gross Motor Function Classification System, ^**p < .001

Table 4. Model suitability of parenting stress

Note. NFI = Normed fit index; CFI = Comparative fit index; TLI = Tucker-Lewis-Index; RMSEA = Root mean square error of approximation.