Long‐term prognosis of low language proficiency in children

Low language proficiency (LLP) affects up to 10% of children and is a known risk factor for academic and social difficulties. A systematic review included 80 studies with approximately 28,828 participants that followed children with LLP identified at ages 4 to 8 years through age 12 and older. Results showed large adverse associations in language abilities (Hedges' g = –1.36) and literacy (g = –1.12) in long-term follow-up. Psychological outcomes showed moderate adverse associations (g = –0.50) with lower probability of favorable psychological outcomes. Social relationships were also negatively affected (g = –0.64), as were environmental outcomes including education and employment (g = –1.10). The research indicates that childhood LLP is not a transient delay but a marker of enduring developmental vulnerability.