Early childhood nutrition is important as it lays the foundation for health in later life. In the context of rapid development and large-scale rural-to-urban migration in China, we evaluated the early childhood nutrition of rural left-behind children using the latest and reliable data. Our work not only extends the observations to children of younger age but also improves our understanding of the association between various parental migration statuses and child nutrition in the current social context.
The findings demonstrate the improvement of early childhood nutrition in recent years in rural China. The estimated risks of stunting, underweight, and wasting among rural infants and toddlers in 2013 in this study are consistent with previous reports during the similar period [10, 15, 16]. A study using the data of 6,136 children aged 0–3 years in central and western China during 2010–2011 showed that the prevalence of stunting among NLBC, FLBC, and PLBC was 16.4%, 15.1%, and 16.6%, respectively . A national survey of the nutritional status of rural left-behind children under 7 years old was conducted among 7,585 left-behind children and 7,557 non-left-behind children from 13 provinces of China during 2008–2009, and found that the prevalence of stunting among under-7-year‑old children with non-migrant, one, and both migrant parents was 16.3%, 14.9%, and 17.9%, that of underweight was 7.6%, 7.2%, and 8.3%, and the prevalence of wasting was 3.3%, 3.1%, and 3.4%, respectively . However, these estimates are lower than the corresponding values derived from the 2016 survey in the current study. In 2016, the estimated prevalence of stunting, underweight and wasting among surveyed children aged 6–35 months in our study were 12.1%, 4.0%, and 1.5%, respectively, which decreased by 26.2%, 52.9%, and 57.1% compared with 2013, respectively, and are lower than other developing countries . Child dietary diversity had also been greatly improved, irrespective of their parental migration status.
Consistent with previous estimates [10, 28, 29], this study also highlights the constantly and alarmingly high risk of anemia among children under 3 years old in rural China. The results show that about two third of children aged 6–17 months and one third of the children aged 18–35 months were anemic, and no significant reduction of risk of anemia was found among these children from 2013 to 2016. Children aged 6–17 months with migrant parents had a significantly lower risk of anemia compared with those living with their mothers or with both parents, which may be attributed to earlier breastfeeding cessation and complementary feeding because of maternal migration. Despite benefits of breastfeeding to child growth and development, prolonged breastfeeding was found to be associated with decreased dietary intakes and increased risk of anemia in infants and young children over 6 months of age [30–34]. This association was not significant at > 18 months of age when most children are weaned from breastfeeding irrespective of the parental migration status. The results also suggest the critical problem in complementary feeding among rural children. Most mothers and caregivers may not have good knowledge about and practices in breastfeeding and complementary feeding [29, 35].
The present study broadly supports the previous findings that parental migration was not significantly detrimental to child nutrition [13, 16, 22, 36] and even confirm the benefits of paternal migration on early childhood nutrition of rural children [13, 37, 38], despite contrary results found in other studies [5, 18, 39]. A decreasing difference in early childhood nutrition between children with various parental migration statuses was shown in recent years, and in the latest survey, no significant differences in risks of stunting, underweight, and wasting were detected between them. Except for the obvious substitution of complementary foods for breast milk among children with migrant parents before 18 months of age, the difference in dietary intake among children with different parental migration statuses also decreased. However, it is worth noting that our findings do not mean that children in rural China are well-nourished or that left-behind children are not vulnerable. Despite the great reduction in risk of macronutrient deficiency, all rural children were still at high risk of micronutrient deficiency such as anemia. In addition, a growing body of literature highlights the need for special attention to the negative effects of parental migration on children’s cognitive and social-emotional development, especially when both parents migrate [40–42].
The mechanism by which parental migration affects child nutrition may be very complex. On the one hand, migration brings economic benefits, broadens the families’ horizons and leads to new life perspectives, which is beneficial to the health of children by increasing health-related investment, improving left-behind caregivers’ mental health, and substantially changed parenting attitude and practices [13, 22, 43, 44]. On the other hand, left-behind caregivers’ increased household tasks  and psychological stress caused by the migration of family members [46, 47], and caregiver rearrangement and changed feeding practices that happens when both parents migrate, can be detrimental to child nutrition. These two effects are working against one another, leading to an uncertain final effect. In our study, FLBC had better household economic status than NLBC in 2013, which may partly account for the lower risk of undernutrition among FLBC; in 2016, they had similar household economic status, and the differences in the risk of undernutrition between them were also of lesser magnitude than those in 2013. However, we found families with migrant parents may be poorer than families with non-migrant parents or with migrant fathers only. This may imply a complex relationship between labor migration and family economics: migration of more family members brings more economic gains but also indicates poorer family economics. Caregivers’ education and depressive symptoms affect child nutrition mostly by affecting feeding practices [48–51]. In our study, compared to caregivers included in 2013, those included in 2016, especially the grandparents who cared for children when both parents migrated, had significantly higher levels of education and less depressive symptoms, which may partly explain the improvement of feeding practices and child nutrition during this period. Increasingly similar determinants between children with various parental migration statuses may also account for their decreasing differences in nutritional outcomes in recent years. It is worth noting that rural areas in China have developed rapidly in recent years, which may greatly contribute to the improvement of child nutrition. Overall, farmers’ income is increasing. Even with limited income, many farmers have improved water, hygiene and sanitation, and renovated their houses with the support of the government. Increasingly convenient transportation, mailing and communication technology also make it easier for migrant parents to participate in child feeding [46, 47, 52–54].
Our study has implications for the formulation of programs and policy to improve child health and development in rural China. First, our results show a high risk of anemia among rural children, regardless of parental migration status, suggesting a broad need for nutritional support for all rural children, especially prevention from micronutrient deficiency. Mothers are suggested to accompany their children in early childhood given the important health benefits of breastfeeding. Nutrition education and some micronutrient fortified foods can be provided to all caregivers. The Chinese government provides special social services for left-behind children as one of the goals of the National Program of Action for Child Development in China (2011–2020) . However, our findings indicate that due to social and economic development, left-behind children may have equal or slightly better nutrition than non-left-behind children. Therefore, programs and policy designed to promote the well-being of left-behind children should pay more attention to other important issues such as cognitive and social-emotional development.
Our study has some strengths. Two large-sample surveys in the same areas were performed to examine the association between parental migration status and early childhood nutrition of children. In each survey, well-established and validated methods were used to measure child nutritional status by investigators blinded to parental migration status and the basic characteristics of the children and their caregivers. However, several limitations also exist. First, the low response rate may bias the results. About 40% of the children in the selected villages were not enrolled in the surveys. According to a rough understanding, the reasons why the caregivers with their children did not participate in the surveys probably include being busy with household tasks, lack of interest or being not at home, etc. Second, we failed to measure some important factors that may moderate the effects of parental migration on the health of left-behind children, such as migration duration, the age of children at the time of the first separation from migrant parents, migrant-caregiver communication, and the number of siblings [53, 56–58]. Third, the interventions of the early childhood development program may confound the analysis of the 2016 survey data, but we controlled for related variables in the regression analyses. Fourth, this study is also limited by its cross-sectional design, and the resulting associations need to be further demonstrated by longitudinal studies. Finally, the generalizability of the results is limited because all participants were from poverty-stricken rural areas of northern and southern China, and about half of them were from three counties of Guizhou Province where a large number of residents are of minorities. In addition, in rural China, many villages have less than 50 children under 3 years of age, which mean the selected villages may not be that representative.
Nevertheless, this study provides information on the changes over time of early childhood nutrition of left-behind children in rural China, and provides new evidence that parental migration is no longer detrimental and even beneficial to the nutrition of these children but all rural children are still at high risk of anemia. Although future programs for left-behind children should continue to focus on nutrition, they should also pay more attention on other important health issues such as mental health. Further research is needed to develop a clearer and full-scale picture of the impact of parental migration on the well-being of left-behind children of all ages.