4. Discussions
We observed that household wealth upward mobility particularly during early life was associated with adolescent higher HAZ and better cognitive development in a birth cohort in an undeveloped setting. Further, adolescents from wealthier households at pregnancy had lower (better) scores of emotional and behavioral problems. Although the interaction We used household assets and dwelling characteristics to construct household wealth index, which is a robust measure in LMICs as compared to income and consumption, suffering from information bias. Our study is one of the few studies to comprehensively assess the mobility and trajectories of household wealth from pregnancy to early adolescence, evaluate adolescent health in multiple domains and examined their relationships in a nuanced manner. Our results show that postnatal household wealth conditional increase could confer the benefits to adolescent HAZ and cognitive development after accounting for the influence of household wealth at pregnancy. Besides, the effect size of household wealth conditional increase between pregnancy and mid-childhood seems to be larger than that between mid-childhood and early adolescence, although with confidence interval overlapping. This finding is in line with the hypothesis that the plasticity of child development is larger during early life, particularly during the first 1,000 days. Another explanation was that school education may have relatively larger impact on adolescent cognitive development as compared to household wealth mobility after mid-childhood/primary school age, given the national strategy of 9-year compulsory education well-implemented in China. In the meantime, some nutritional intervention programs were conducted among school, e.g., the Yingyangbao strategy widely covered in rural areas in China (In addition, the potential benefits of household wealth increase over time may differ by specific health outcome. We observed consistent significance for adolescent HAZ and cognitive development which may result from the appropriate infant feeding, diets, stimulation, and home environment among higher wealth households, all of which have been shown to be causes of child linear growth and development (Furthermore, we examined the modifications of parent education and offspring sex on the relationship between household wealth mobilities and adolescent health, although majority of these interaction Our findings have a few limitations. Firstly, adolescents were born to mothers who had participated in an antenatal micronutrient supplementation trial which might limit the generalization. However, this community-based trial enrolled all eligible pregnant women in every village and we adjusted for randomized regimens in all analyses. Besides, this micronutrient intervention strategy would be expected to weaken the tie between household wealth and adolescent health for its ability to reduce the wealth-driven equity (Higher prenatal household wealth and postnatal household wealth increase particularly during early life had wide benefits on adolescent HAZ and cognitive development, and possibly socioemotional outcomes. To improve adolescent health and human capital outcomes, public health programs targeting at all life-course stages are warranted and should be accompanied by strategies to reach the most vulnerable populations at the beginning of pregnancy. Given the importance of household wealth and other related SES indicators in child health, it is recommended that socioeconomic circumstances should be routinely documented in the healthcare record.