This is considered a "critical period" in which sufficient nutrition and environmental factors have life-long effects on a child's overall health.
[1] Medical and public health interventions early on in child development during the first 1,000 days may have higher rates of success compared to those achieved outside of this period.
In underserved communities where families may face food insecurities or poor living conditions, the risk of undernutrition and negative affect to microbial pathway may increase.
Both maternal and early-childhood nutrition influence epigenetic changes, which then inform immunologic and metabolic outcomes throughout development and into later life.
[13] Present in human milk are HMOs, bioactive components which aid in immune function and regulation, and miRNA-containing exosomes.
HMOs can be fermented into short-chain fatty acids, which play important roles in modulating the microbiome and in T cell differentiation, and may positively correlate with methylation levels.
[16] Exposure to emotional, physical, and environmental stressors significantly affect the developing brain, which may later manifest in negative mental- and health-related outcomes through the HPA axis' role in stress regulation.
Smoking in pregnancy is associated with differential methylation of genes implicated in brain development, central nervous system disorders, asthma, and various cancers.
[1] Other forms of childhood adversity, which include abuse or neglect, similarly impact a child's development through differential epigenetic programming and stress response dysregulation.
In addition to adverse effects on mental health, children who experience these events often exhibit dampened immune responses.
There are some macronutrients, micronutrients, and vitamins that may be better obtained and retained if acquired through breastfeeding which is why it is crucial that mothers maintain adequate nutrition post delivery.
[27] This includes: Vitamin A, which is key for fetal development, organogenesis, limb formation, immune functions, mucosal integrity and body symmetry.
Overall, adequate nutrition within the first 1,000 days is a responsibility shared by caregivers (e.g. parents), as well as providers (e.g. pediatricians, social workers, dieticians).
This is partially due to the fact that the complementary diet comprises the largest fraction of dietary development, but particularly because transitioning from liquid to solid foods presents a challenge of its own.