Parents of children with developmental disabilities often face greater challenges than those whose children have other illnesses (Ljubičić et al., 2022), primarily due to the constant uncertainty they encounter. Various factors significantly contribute to this uncertainty. For instance, during the early stages of a developmental disability diagnosis, parents frequently experience social isolation due to stigma, which limits their access to critical information and intensifies their sense of uncertainty (Sartore et al., 2021). Additionally, previous studies suggest that as the severity of their child's developmental disability increases, mothers are more likely to reduce their working hours or leave their jobs (Amaro et al., 2024). This reduction in work often leads to financial instability, including decreased income and challenges in planning for retirement (Agarwal et al., 2023). Furthermore, parents frequently face uncertainty stemming from marital conflicts (Brisini & Solomon, 2020) and the need to adapt to changing family dynamics (O'Brien, 2016; Sartore et al., 2021).

These challenges are closely tied to the lifelong caregiving responsibilities that begin in early childhood, when developmental issues first become apparent and continue through school age, adolescence, adulthood, and beyond (Song et al., 2018). This uncertainty permeates all aspects of life, encompassing challenges related to support from schools, welfare services, and the healthcare system, as well as decisions about appropriate parenting strategies (Oulton et al., 2022; Scherr et al., 2020; Siddiqua & Janus, 2017; Wong & Wong, 2021). In essence, the chronic nature of developmental disabilities, combined with the overwhelming caregiving responsibilities and the uncertainty of navigating an unfamiliar developmental journey, significantly intensifies the difficulties such parents face (Ljubičić et al., 2022; Scheibner et al., 2024; Seymour et al., 2025).

Addressing uncertainty is particularly important for parents of children with developmental disabilities because it underlies many of the mental and physical health issues they encounter. The literature indicates that this uncertainty affects marital conflict (Brisini & Solomon, 2020), caregiving burden (Jeong & Suk, 2023), adaptation (O'Brien, 2016), quality of life (van Nimwegen et al., 2016), parenting efficacy (Yang & Yu, 2022). Effective interventions targeting this uncertainty can thus significantly improve marital relationships, quality of life, adaptation to the child's condition, and overall family well-being, potentially yielding personal growth and a healthier life outlook.

A reliable and valid scale is essential in effectively evaluating the uncertainty faced by parents of children with developmental disabilities. Several tools have been developed to measure uncertainty, with one widely used instrument in nursing being the Uncertainty in Illness Scale (Mishel, 1981), associated with Mishel's uncertainty in illness theory (Mishel, 1988). Mishel (1983) later adapted this tool to measure the uncertainty perceived by parents of children with illnesses. She defined uncertainty as a cognitive response, describing it as “the inability to determine the meaning of illness-related events” (Mishel, 1988). The Parents' Perception of Uncertainty in Illness Scale (PPUS) was developed to assess the uncertainty experienced by parents of hospitalized children. It encompasses four factors— ambiguity, unpredictability, lack of clarity, and lack of information—measured using 31 items on a 5-point Likert scale (Mishel, 1983).

The PPUS has been translated into several languages, including Chinese, Arabic, and Spanish, and has been extensively used in numerous studies (Al-Yateem et al., 2017; Suarez-Acuña et al., 2018; Ye et al., 2017). A Korean version of the scale was translated in a 1997 master's thesis, with its content and construct validity verified through exploratory factor analysis (EFA) (Oh, 1997). However, there are several limitations in applying Oh's (1997) Korean translation to parents of children with developmental disabilities. First, as the translation was originally developed for parents of hospitalized children, its validity is difficult to generalize to parents of children with chronic conditions, such as developmental disabilities. Second, certain items in the PPUS do not reflect the chronic nature of developmental disabilities or the specific characteristics of the institutions where these children typically receive treatment, making some terms uncomfortable or irrelevant for parents. Therefore, applying the PPUS to parents of children with developmental disabilities requires not just translation but also cultural adaptation tailored to this condition.

Thus, this study aimed to translate and culturally adapt the PPUS into Korean for use with parents of children with developmental disabilities and to evaluate the psychometric properties of the translated version. Specifically, the study followed a validated translation procedure while ensuring the validity and reliability of the translated PPUS by evaluating its psychometric properties, including content validity, construct validity, convergent validity, discriminant validity, model fit, and reliability. This study sought to provide a reliable tool for accurately assessing parents' perceived uncertainty, laying the groundwork for subsequent research, such as effective intervention planning. Furthermore, it is anticipated that, as these follow-up studies enhance parents' mental health, this study will ultimately contribute to improving the health of children with developmental disabilities.