Moving up but not getting ahead: Family socioeconomic position in pregnancy, social mobility, and child cognitive development in the first seven years of life.

Objectives: Understanding when and how socioeconomic position (SEP) influences cognitive development is key to reducing population inequalities in health and achievement. The objective of this study was to determine the unique association between prenatal family SEP and child cognitive development, and to determine whether marked postnatal social mobility was associated with improvements in child cognitive performance to age 7. Methods: Data were from children enrolled in the US National Collaborative Perinatal Project (NCPP) (n = 28,761) during 1959-1965, a dataset large enough to observe marked mobility, which remains uncommon. Multivariable linear regression was used to examine the relationship between SEP (i.e., parental income, education, occupation) during gestation and cognitive performance at 8 months (Bayley Scales of Infant Development Mental Development Index) and at 7 years (Wechsler Intelligence Scale for Children). Results: Holding demographic and perinatal factors constant, family SEP during gestation was not associated with cognitive performance at 8 months (B = -0.03, 95% CI: -0.07-0.01) but was positively associated with performance at 7 years even after accounting for SEP at 7 years (B = 1.28, 95% CI: 1.11-1.45). Children whose families experienced the most extreme upward mobility (from the lowest to highest income quartile) showed a 12 percentile increase in cognitive performance in the first 7 years of life. Those with the most extreme downward mobility (from the highest to lowest income quartile) still experienced an 8 percentile increase in cognitive performance in this interval. Conclusions: The proportion of children in poverty today is similar to 1965 and intergenerational mobility has declined markedly. Prenatal SEP may contribute to inequalities in child cognitive performance that even extraordinary social mobility cannot erase. To optimize cognitive development across generations, current means-tested programs to support families with young children should be supplemented by universal approaches to ensure access to opportunity before young people become parents.