Gestational age, kindergarten‐level literacy, and effect modification by maternal socio‐economic and demographic factors

• Published in: Paediatric and perinatal epidemiology 2019-11, Vol.33 (6), p.467-479
• Main Authors: Mallinson, David C., Grodsky, Eric, Ehrenthal, Deborah B.
• Format: Article
• Language: English
• Subjects: Age; Benchmarks; Births; Children; Confidence intervals; Demographics; Economics; Education; effect modification; Gestational age; Government programs; health disparities; Kindergarten; life course; Literacy; Medicaid; Minority & ethnic groups; Premature birth; preterm birth; Screening; Skills; Statistical analysis
• ISSN: 0269-5022; 1365-3016
• DOI: 10.1111/ppe.12588

Background Shorter gestational age at birth is associated with worse academic performance in childhood. Socio‐economic and demographic factors that affect a child's development may modify the relationship between gestational age and later academic performance. Objective The purpose of this study was to investigate socio‐economic and demographic effect modification of gestational age's association with kindergarten‐level literacy skills in a longitudinal Wisconsin birth cohort. Methods We sampled 153 145 singleton births (2007‐2010) that linked to Phonological Awareness Literacy Screening—Kindergarten (PALS‐K) scores (2012‐2016 school years). PALS‐K outcomes included meeting the screening benchmark (≥28 points, range 0‐102 points) and the standardised score. Multivariable linear regressions of PALS‐K outcomes on gestational age (completed weeks) included individual interactions for five maternal attributes measured at delivery: Medicaid coverage, education, age, race/ethnicity, and marital status. Results Each additional completed gestational week was associated with a 0.5 percentage point increase in the probability of meeting the PALS‐K literacy benchmark. The benefit of an additional week of gestational age was 0.5 percentage points (95% confidence interval 0.3, 0.7 percentage points) greater for Medicaid‐covered births (0.8 percentage points) relative to non‐Medicaid births (0.3 percentage points). Relative to only completing high school, having college education weakened this association by 0.3‐0.6 percentage points, depending on years in college. Similar but modest relations emerged with standardised scores. Conclusions Socio‐economic advantage as indicated by non‐Medicaid coverage or higher levels of completed maternal education may diminish the cost of preterm birth on a child's kindergarten‐level literacy skills.