Preterm is defined as babies born alive before 37 weeks of gestation. The rate of preterm birth (PTB) ranges from 4% to 16% for babies born in 2020 across different countries. Globally, prematurity is the leading cause of death in children under the age of 5 years [1]. It is a significant public health concern worldwide. In Korea, the rate of PTB has been increasing, with a recorded rate of 9.8% in 2022, showing a 0.6% increase from the previous year and a 1.6-fold increase compared to a decade ago [2]. Among PTB cases, preterm labor accounts for over 40.0% [3].

Preterm labor is characterized by regular uterine contractions accompanied by changes such as cervical dilatation or loss with a minimum cervical dilatation of 2 cm [4]. Maternal stress has been identified as one of the contributing factors to preterm labor [5]. Chronic stress resulting from unresolved stressors over an extended period can have detrimental effects, particularly during pregnancy [6].

Daily stress is defined as mundane hassles, strains, or annoyances associated with routine daily activities and transactions of everyday life. Although daily stress is relatively minor, it has the potential to disrupt the flow of everyday life and add to overall levels of stress [7]. Some researchers have operationally defined prenatal stress as the number of major life events or daily hassles during pregnancy [8]. Increasing attention has been paid to the role of psychosocial factors in the etiology of PTB. Among such factors, stress increases the risk for poor birth outcomes including PTB, so further research is needed on various forms of stress, including chronic stressors, major life events, and daily hassles/perceived stress [9]. It is important to note that any stress perceived by pregnant women can increase the secretion of cortisol and cytokines, which may stimulate prostaglandin secretion and consequently lead to preterm labor [10]. Lifestyle changes in urbanization, health behavior, physical activities, employment, working condition, tobacco use, alcohol use, and illicit drug use can also affect psychosocial stress [11]. Perceived stress refers to feelings or thoughts that an individual has about how much a stress event or situation generates at a given point in time or over a given time period [12]. Perceived pregnancy stress has been identified as a contributing factor to PTB [13]. Impact of life event stressors on preterm birth depends on the timing of stressor and self-perceived stress [14]. Thus, it is crucial to investigate the impact of both pregnancy-specific stress and life event stress on preterm labor. Furthermore, stress tends to have a stronger effect when multiple factors of stress act simultaneously rather than individually [15, 16]. Hence, it is necessary to examine the cumulative effect of pregnancy-specific stress and daily hassles stress.

On the other hand, self-efficacy refers to an individual’s belief in their ability to successfully perform a task and achieve specific results in a given situation [17]. Self-efficacy represents a way to self-control an individual’s emotions which can bring multiple advantages in the area of stress. It is a variable that can reduce stress [18]. Higher level of self-efficacy measured by the general self-efficacy (GSE) scale is associated with lower levels of stress among pregnant women [19, 20, 21, 22]. Therefore, it is essential to measure GSE alongside stress in preterm labor pregnancies. However, to the best of our knowledge, existing studies investigating stress or self-efficacy [19, 22] have primarily focused on pregnancy-specific stress, neglecting the examination of daily hassles stress. Additionally, few studies have explored the moderating effect of GSE on stress in preterm labor pregnancy.

Thus, this study aimed to investigate the moderating effect of GSE in pregnant women experiencing preterm labor. By examining the relationship between pregnancy stress, daily hassles stress, and PTB risk, whether GSE might have a protective effect in mitigating the impact of stress on PTB risk was determined. Understanding the moderating effect of GSE in this context can provide valuable insights to healthcare providers in developing interventions and support strategies to reduce PTB risk in preterm labor women.

The primary goal of this study aimed to investigate moderating effects of GSE on the relationship between pregnancy stress and daily hassles stress, and PTB risk in women experiencing preterm labor. Our results revealed a several key insights that deepen our understanding of these interactions.

The mean age of women experiencing preterm labor in this study was 32.7 years. In terms of the relationship between age and preterm labor, we observed a significantly higher PTB risk in women aged 40 years or older compared to those in their 20s. This result supports previous research suggesting increased PTB risks associated with advanced maternal age [31, 32]. These findings underscore the need for healthcare providers to tailor monitoring and intervention strategies for older pregnant women.

Next, let’s discuss the impact of stress on PTB risk. According to Bandura’s theory of self-efficacy, higher GSE may lead individuals to perceive stressful situations as more manageable, thereby potentially mitigating the adverse effects of stress [17]. However, our study suggests this relationship can be complex and may not always act protectively, especially under high stress levels. In this study, both pregnancy and daily hassles stress contribute significantly to PTB risk, with GSE playing a moderating role. Interestingly, higher levels of GSE were associated with an amplified response to stress, particularly at higher stress levels, potentially supporting the idea that high GSE could alter stress responses [33], challenging the conventional view of GSE as solely protective. This suggests that while GSE can enhance coping capacities, it may also exacerbate stress responses under high-stress conditions, leading to increased PTB risk.

On the other hand, comparing daily hassles stress with prior studies was challenging due to the limited research. However, our findings suggest that daily hassles stress is more pronounced in pregnancies with preterm labor compared to general adult women [34]. This emphasized the need to address both pregnancy-specific and daily hassles stress in prenatal care. Furthermore, it is worth noting that various terms such as "daily life stress", "life stress", and "life event stress" have been used interchangeably with "daily hassles stress" [27]. Therefore, researchers should strive to unify these terminologies and develop a suitable scale specifically designed for pregnant women, including those experiencing preterm labor.

Regarding the relationship between both stresses and GSE, daily hassles stress showed a negative correlation with GSE, while pregnancy stress exhibited no significant relationship with GSE in our study. This finding aligned with a study by Pasha et al. [22]. Previous studies [22, 35] have demonstrated that individuals with higher GSE tend to perceive stress as being lower, different from this study results.

The complex role of GSE observed in our study suggests a dual-edged nature: GSE can be beneficial under lower stress conditions but may intensify stress responses as stress levels escalate. This finding indicates that interventions aimed at enhancing GSE should be carefully tailored to individual stress levels and coping mechanisms.

Given the complex interplay between GSE, stress, and PTB risk, further research should explore additional factors influencing this relationship and develop interventions that adjust to the varying impacts of GSE. Additionally, our study highlights the importance of comprehensive stress management strategies in prenatal care that consider individual differences in GSE.

However, it is crucial to recognize certain limitations of our study. This study’s methodology, particularly the exclusion of specific scale items and the use of a general rather than a childbirth-specific efficacy scale, may limit the applicability of our findings across all cases of preterm labor.

Additionally, employing a GSE scale rather than a childbirth efficacy scale might limit the applicability of our results across all preterm labor cases. Future research should consider incorporating a childbirth efficacy scale [36] to facilitate a direct comparison between childbirth efficacy and GSE. Despite these limitations, our study is pioneering in examining the intricate role of GSE in the stress-PTB risk dynamic, paving the way for further exploration of this important area.

Our research explored how pregnancy stress and daily hassles stress affect women facing preterm labor and examined the role of GSE plays in moderating these stresses and their combined impact on the risk of PTB. Contrary to expectations, higher GSE was found to amplify the effect of stress on PTB risk. This revelation prompts several recommendations for clinical practice and further study.

Firstly, there’s a need to investigate how different levels of GSE impact the stress response in such contexts, which could inform targeted support and intervention strategies. Secondly, future studies should aim to include a wider range of participants to uncover additional individual and contextual factors affecting PTB risk. Lastly, considering the notable impact of daily hassles stress, identifying and addressing these stressors in tailored ways could be key to managing PTB risk effectively.

In summary, this study enhances our understanding of the interactions among stress, GSE, and PTB risk in the context of preterm labor. These insights pave the way for healthcare providers and researchers to develop precise interventions and support systems, aiming to improve outcomes for women susceptible to PTB.

Supplementary data to this article can be found online at https://doi.org/10.4040/jkan.24008.

Supplementary Table 1

Moderating Effect of General Self-Efficacy on Impact of Pregnancy Stress on Preterm Birth Risk (N = 196)

Supplementary Table 2

Moderating Effect of General Self-Efficacy on Impact of Daily Hassles Stress on Preterm Birth Risk (N = 196)

Supplementary Table 3

Moderating Effect of General Self-Efficacy on Impact of Pregnancy Stress and Daily Hassles Stress on Preterm Birth Risk by Hierachical Regression (N = 196)