Maternal iron status during pregnancy: relationship with fetal growth; ECLIPSES study.

From conception through early childhood, the developing brain is highly susceptible to influence from the family and social environment []. Socioeconomic status (SES) encompasses more than a family’s economic resources; it also reflects social standing, prestige, and the broader environmental context. Differences in SES-including disparities in income, education, occupation and wealth- exert a substantial impact on children’s neurodevelopment [, ]. These SES-related inequalities constitute major barriers to equitable infant development. Previous researches have demonstrated associations between SES and both structural and functional brain development in infants, using developmental assessments and neuroimaging [–]. For instance, lower SES has been linked to reduced gray matter volume in key brain regions, particularly in the frontal and occipital lobes []. Although SES is a multifaceted construct encompassing income, education, occupation, and overall wealth [, ], many studies assessing its relationship with neurodevelopment capture only limited aspects of this complexity, thereby providing an incomplete picture []. SES is recognized as a critical social determinant of child development []. Much of the prior literature has focused on SES-related influences during childhood and adolescence [, ], and has proposed explanatory frameworks such as the parental investment model and the parental stress model [, ]. However, evidence suggests that SES begins to affect neurodevelopment as early as infancy, underscoring the importance of timely early interventions []. Yet, few studies have comprehensively examined, within the same population, the roles of both prenatal and postnatal factors in the association between family SES and infant neurodevelopment within the first 12 months of life. Accumulating evidence has documented that multiple modifiable prenatal and postnatal factors may lie on the pathway between family SES and early infant neurodevelopment. Prenatal maternal mental health problems, such as anxiety and depression, are more prevalent among women with disadvantaged socioeconomic backgrounds [, ] and have been recognized as critical predictors of impaired fetal brain development and subsequent neurodevelopmental performance in offspring [, ]. Similarly, women from low-SES backgrounds have higher risks of gestational hypertension, preeclampsia, and gestational diabetes []. These complications have, in turn, been consistently linked to adverse neurodevelopmental outcomes in offspring []. Suboptimal birth outcomes (e.g., preterm birth, low birth weight) are strong predictors of later neurodevelopmental impairments [, ]. Evidence suggests that socioeconomic disparities contribute to variations in birth outcomes [], which may also be shaped by maternal pregnancy complications [] and prenatal psychological status []. Beyond pregnancy, resource constraints in low-SES families often extend into the postpartum period, manifesting as less supportive caregiving environments, suboptimal parenting practices, and lower-quality parent-child interactions. These conditions can affect infant cognition, language, and motor development, thereby disrupting early neurodevelopment [, ]. Moreover, most existing studies on SES-related developmental disparities have been conducted in Western populations. Therefore, we investigated these associations in a Chinese population to inform culturally appropriate public health interventions.