Turning 1 Year of Age in a Low Socioeconomic Environment: A Portrait of Disadvantage.

Only 52 of the 60 enrolled infants were analysed at 12 months. The sample was restricted to healthy term African American female infants and their mothers in an inner-city setting, so findings may not apply to boys, other racial or ethnic groups, rural families, or infants with medical risk. The Higher SES group was still relatively low income, with 60% near poor and only 40% above low income, so the comparison may underestimate differences against truly higher-income families. The study cannot separate genetic and environmental influences, because maternal cognitive scores were lower in Low SES and the design did not determine whether those scores reflect inherited or environmental factors. Risk categories for some environmental factors were based on this sample's distribution rather than validated external thresholds. The study was designed to detect large differences (0.8 SD) and may have been underpowered for combined effects of SES and environmental factors. No intervention was tested, so the study cannot show that changing home, neighborhood, or maternal factors will improve infant development.

Do not read these lower scores as proof that poverty causes developmental delay or that improving one environmental factor will raise scores. This was an observational study of 52 healthy African American girls, and once SES group was included in the statistical models, measured environmental factors were not significantly associated with outcomes.