Premature birth is defined as the termination of pregnancy before 37 weeks of gestation [1]. According to the World Health Organization (WHO), approximately 15 million premature babies are born worldwide every year. Incidence of premature birth ranges from 5–18% in 184 countries [2] and continues to increase [3]. Currently, the number of premature babies born annually in China is 1,172,300, accounting for 7.81% of the worldwide total. Additionally, China has the second highest premature birth rate in the world. Owing to the continuous introduction of birth policies, the premature birth rate is inclined to accelerate [2]. As the proportion of older mothers increases, the likelihood of pregnancy complications also increases, contributing to an increase in premature birth rates. In addition, premature birth is the primary cause of neonatal death. Premature birth-related complications cause one million deaths annually, accounting for more than 50% of neonatal deaths [3]; moreover, the mortality rate of premature infants is 12 times that of full-term infants [4]. In recent years, mortality rates have decreased owing to development of advanced medical technology, improvements in perinatal care programs, and establishment of neonatal intensive care units. However, premature birth leads to shortened gestation time, insufficient foetal nutritional reserve, dysplasia of various body systems, and weakened postnatal immune function. Compared with full-term infants, premature infants experience problems such as insufficient lung maturity, unstable blood flow, neurodevelopmental delay, and fragile blood vessels, which lead to low resistance to the external environment after birth, making them prone to complications [5]. Further, short- and long-term sequelae caused by premature birth impact adult mortality [6]. Most premature babies require Neonatal Intensive Care units (NICUs) because of their vulnerable physical condition; NICUs promote organ maturation, enhance immunity, and improve long-term survival. In addition to inducing various complications, the frequent medical operations required by premature infants generate huge costs. The retrospective analysis of Thanh et al. found that although premature infants accounted for only 7% of all newborns, the total medical costs incurred were as high as 37% [7]. Premature infants consume more health resources in terms of initial hospitalisation, as well as rehospitalisation, outpatient services, and medical treatment, in the first year after birth [7, 8]. Unstable physiological conditions, unpredictable disease development, and high medical costs are strong sources of stress that can cause familial trauma [9]. In addition, stressors such as parental role change, parent-child separation, lack of knowledge of diseases, and high medical costs greatly impact the psychology of parents. During this period, their needs often remain unmet, leading to various negative emotions such as anxiety, depression, perceived vulnerability, and post-traumatic stress disorder [10, 11].
Psychology directs and promotes behaviour. Previous studies have focused on examining negative psychological effects on individuals; however, in recent years, the impact of positive psychological experiences has been considered as well. Parents going through premature birth often experience pressure, since they bear the primary responsibility for this adverse and unexpected event. Moreover, caregivers' reflection and growth after the event directly affects children’s coping ability and disease prognosis, owing to their young age. Premature birth threatens the life and health of mothers and children, causes familial trauma, and seriously affects parents’ post-traumatic growth (PTG). The negative emotions associated with trauma hinder PTG, and post-traumatic stress disorder may occur in severe cases. Post-traumatic stress disorder is common among parents of children in neonatal intensive care units, and the severe physiological conditions and uncertain prognosis of the foetus after birth aggravate its occurrence, hindering treatment and growth in children [12]. Parental PTG is crucial to facilitate early response in hospitals, growth and development of premature infants after discharge, and family recovery. Parents of premature infants may experience helplessness and worry due to the closed medical environment and lagging disease knowledge during hospitalisation, as well as the potentially high risk of complications after discharge. As parents are the main caregivers of newborns after discharge, continuous psychological problems can affect their mental health and seriously hinder self-perception of their role and caring ability [13, 14]. This is not conducive to the family's recovery, and can affect growth and development of premature infants, thus forming a vicious circle.
To cope with the change in circumstances pre- and post-discharge, the parents moved from focusing on the pain caused by the event to thinking about possible causes and ways to solve the problem; subsequently, their values and priorities changed. They re-established relationships with friends, family, and medical staff, thereby receiving external psychological, material and social support to cope with traumatic events. Throughout the process, they demonstrated active medical cooperation and a strong demand for knowledge. Furthermore, a family's ability to cope with external stressors also plays an important role in positive parental psychology and behaviour, effectively reducing the family's worries and improving efficiency of action. Positive psychological and behavioural changes lead to parental PTG. In addition to the physical and mental health of family members, PTG levels are closely related to prognosis of premature infants. Low PTG levels affect the development of premature infants, and a poor prognosis causes familial trauma; these two factors influence each other. Currently, most patients being researched are adult cancer patients [15], and most studies on PTG in parents have focused on cancer [16], autism [17], and congenital diseases [18]. Limited studies on children and their caregivers exist; consequently, investigations on PTG in parents of premature infants remain insufficient. Therefore, this study aimed to investigate the status quo and influencing factors of PTG in parents of premature infants born in the NICU; explore the correlation between PTG levels and rumination, perceptive social support, and family resilience; promote the clinical development of targeted intervention measures; and make full use of favourable factors to improve parents’ mental state. Further, we aimed to promote the prognosis of children and family health.