Early development consists of critical periods during which
children are vulnerable to exposures.34 Delays in
children's development occur cumulatively and start as early as conception, which supports arguments for early investments.35 The impact of different nutrients on
children's development depends on timing, dose and duration of deficiencies.8, 36 Parenting practices and home environments also influence
child development and may either accentuate or attenuate the effects of
poverty, which directly affects
child outcomes.37 Thus, potential intervention effects can
vary according to timing, exposures and environmental conditions.38 For these reasons, it is important to consider trajectories of
child development across a spectrum of ages, not just any one age.39
Varying treatment intensity in a home - based parent and
child therapy program for families living in
poverty: A randomized clinic trial.
For example, compared to older mothers, teen mothers display lower levels of verbal stimulation and involvement, higher levels of intrusiveness, and maternal speech that is less
varied and complex.47, 48 Mothers with fewer years of education read to their
children less frequently25, 49 and demonstrate less sophisticated language and literacy skills themselves, 50 which affects the quantity and quality of their verbal interactions with their
children.2 Parental education, in turn, relates to household income:
poverty and persistent
poverty are strongly associated with less stimulating home environments, 51 and parents living in
poverty have
children who are at risk for cognitive, academic, and social - emotional difficulties.52, 53 Finally, Hispanic and African American mothers are, on average, less likely to read to their
children than White, non-Hispanic mothers; 54 and Spanish - speaking Hispanic families have fewer
children's books available in the home as compared to their non-Hispanic counterparts.25 These racial and ethnic findings are likely explained by differences in family resources across groups, as minority status is often associated with various social - demographic risks.