Our findings revealed that children in low SES households had a higher risk of early developmental delay; the prevalences of SDD and SEDD were 41.2% and 42.1% among children with low SES. Compared to the children in high-SES households, the children with low-SES families had the highest risk of SDD (OR = 1.92) and higher risk of SEDD (OR = 1.31). The positive association between SES and caregiver-child interaction was also significant (P<0.05). Furthermore, high-quality caregiver-child interaction attenuates the adverse effects of low SES on child developmental delay, and the caregiver-child interaction partially mediated the association of SES with the child's early neurodevelopment and social-emotional development. We also found that caregiver-child interaction moderated the associations of SES with children’s neurodevelopment, especially in boys. Therefore, intervention programs strengthening caregiver-child interaction was urgently needed in rural country.
Children in low SES households had a higher risk of early developmental delay. Although fewer than 6 million under-5 child deaths occur each year, about 43% of children in low- and middle-income countries (LMICs) are at risk of not reaching their developmental potential due to stunting and poverty alone[26]. A poor start in life limits children’s abilities to benefit from education, which may lead to long-term adverse effects such as lower productivity and social tensions. Consequences affect not only present but also future generations[5]. As a predictor of poverty, SES was associated with a wide range of health, cognitive, and socioemotional outcomes in children, with lasting effects from birth to adulthood[6]. In our study, we found that children in low SES households in rural China were more susceptible to early neurodevelopmental delay and social-emotional behavior problems, and the prevalence of SDD and SEDD reached 41.2% and 42.1%, respectively. Our findings were consistent with a cross-sectional survey of children aged 36–60 months in Iran that revealed the SES index could be used to interpret the inequalities of child development[6]. A prospective cohort study documented that low SES (e.g., maternal lower levels of education, low income, and poor housing conditions) is significantly correlated with child developmental delay[27]. The mechanisms linking SES to child development involve the differences in access to material and social resources or reactions to stress-inducing conditions by the children and their parents[6]. Low SES would increase the risk of unhealthy behaviors, inadequate nutrition, failure to access health care, maternal diseases, and drug abuse, consequently increasing child developmental delay[28]. Furthermore, children with low-income families are more exposed to family conflict, violence, separation, and instability, posing adverse effects on their development[29]. Although China has scored a complete victory in eradicating absolute poverty in 2020, there are still a large number of vulnerable individuals living with disadvantages and suffering from developmental delay risk. In the phase of rural revitalization in China, more emphasis should be attached to the development situation of children living in low-SES families to consolidate the achievements of poverty alleviation. Although several ECD programmes, such as home visiting services and ECD centers establishment, have been launched by government departments or some other organizations, the coverage is minimum and the effectiveness remains unknown. Cost-effective ECD interventions should be further explored to narrow the children’s development inequality and inadequacy in rural-urban.
High-quality caregiver-child interaction attenuates the adverse effects of low SES on child developmental delay. Determinants for development in early life can be found among biological and socioeconomic factors, and in stimulation and learning opportunities[30]. Evidence documented that stimulating caregiver-child interactions, including smiling, touching, talking, storytelling, listening to music, sharing and reading books, and engaging in play, are highly beneficial for early childhood development and have long-lasting positive effects[14]. Studies have emphasized a relationship between SES and children’s cognitive and linguistic learning through family simulations, the number of siblings, and the number of family members who live together[31]. Our study revealed that the caregiver-child interaction partially mediated the association of SES with the child's early neurodevelopment and social-emotional development. In other words, the adverse effects of low SES on child developmental outcomes could be attenuated by increasing caregiver-child interaction. Evidence showed that nutrition, home environment, child-parent interaction, and facilitating and stimulating learning experiences affect child development, and higher SES would lead to a better learning environment, while lower SES is a barrier to learning and accessing cognitive stimulation such as accessing newspapers, books, and toys[6]. Therefore, receiving stimulation and interaction during infancy and early childhood is vital to successful development[32]. Our study reinforced the importance of the quality of caregiver-child interaction on children’s early development in low SES families in rural China, providing ECD intervention tailored to our country.
Intervention programs strengthening caregiver-child interaction was urgently needed in rural country. ECD intervention programmes have been launched worldwide as a vital effort to achieve the UN Sustainable Development Goals. Evidence revealed that investment in ECD benefits longer-term health, learning, and behavior[26]. In China, to ensure high-quality nurturing care in rural families and narrow the early development gap between urban and rural children, the government has developed a range of Early Child Development programmes since 2009. Children's nutrition status (e.g., stunting, underweight, and wasting) in poor rural China has been greatly improved after the nutrition supplement program called Ying Yang Bao across the country[33]. However, a shortage of early stimulation is a severe issue, especially in less-developed rural areas. A survey conducted in the least developed province of China indicated that more than two-thirds of caregivers have no interaction activities (e.g., play or reading) with their child[19]. Our study expanded the evidence that higher risk of developmental delay and poor nurturing environment among children aged 0–6 were still challenging in rural China even after eradicating absolute poverty across China. Moreover, our study suggested that opportunities for early learning, including adequate caregiver-child interaction, could attenuate the detrimental effects of low SES on child development. Low-cost activities, such as storytelling, singing, and playing with household objects, expose young children to experiences that promote early development[34]. Therefore, actions should be taken to improve caregivers’ awareness of the importance of daily interaction with their children, especially those caregivers with low SES.
Our study had several strengths and limitations. To our knowledge, this is the first study conducted in the context of poverty alleviation across China to evaluate the effect of caregiver-child interaction on the association of SES with child development, which provides solid evidence for future intervention research. Besides, the study population in our research was representative and covered from two months to six years old and included 103 villages. Moreover, our study simultaneously evaluated the child's early neurodevelopment and social-emotional development, which could comprehensively understand the development of rural children. However, certain limitations of this study should be recognized. First, because of the cross-sectional design in this study, we were not able to assess the causal associations of the nurturing environment (e.g., SES and caregiver-child interaction) with early childhood development, and a further cohort study is needed to demonstrate those relationships. However, our large random sample size and precise results provided several answers that can move our understanding of associations among the three variables. Second, as the self-reported data by the caregiver may lead to under-reporting, it’s inevitable for information bias to occur. Third, we do not assess the roles of caregiver-child interaction between parent migration and non-migration. Future research could consider this variable to better uncover the development situations of vulnerable children with migration parents.