Socioeconomic (SES) differences in language are evident in female infants at 7 months of age

•Examined early effects of low and higher SES environment in a cohort of healthy, female, African American infants•Tested birth cohort of 54 infants in longitudinal follow-up at 7 months of age•Low SES infants performed less well than Higher SES on language skills.•Maternal vocabulary was correlated with SES and but not infant language function.•Interventions are needed to address risk factors associated with SES discrepancies in early language skills.

BackgroundLanguage skills, strongly linked to academic success, are known to differ by socioeconomic status (SES), with lower SES individuals performing less well than higher SES.AimsTo examine the effect of SES on infant language at 7 months of age and the relationship between maternal vocabulary skills and infant language function. To determine if the relationships between SES and infant language are mediated by maternal vocabulary skills.Study designLongitudinal follow-up of healthy term female African American infants born to mothers in two SES groups: Low SES (income-to-needs ≤ 1, no education beyond high school) and Higher SES (Income-to-Needs > 1, at least a high school diploma).Subjects54 infants tested at 7 months of age; 54 mothers tested at infant age 7 months.Outcome measuresPreschool Language Scale-5 (PLS-5), Vocabulary and Matrix Reasoning subtests of the Wechsler Adult Intelligence Scale-IV.ResultsLow SES infants (n = 29) performed less well than Higher SES (n = 25) on PLS-5 Total Language, Auditory Comprehension, and Expressive Communication (p ≤ 0.012). Maternal Vocabulary subtest scores were lower in Low SES than Higher SES (p = 0.002), but not related to infant PLS Language scores (p ≥ 0.17). Maternal vocabulary did not mediate the relationship between SES and infant language skills at age 7 months.ConclusionsIn this single sex and race cohort of healthy, term, female infants, lower SES exerted negative effects on infant language by 7 months of age. While maternal vocabulary scores showed no relation with infant language skills at 7 months, continued study of the relations between SES, infant outcomes and maternal characteristics is needed to determine how low SES conditions impact early language. These findings underscore the importance of early interventions, as well as policies designed to improve socioeconomic conditions for infants and families.