To estimate the association between small for gestational age (SGA) at birth and educational performance on standardized testing and disability prevalence in elementary and middle school.

Through linked birth certificates and school records, surviving infants born at 23-41 weeks of gestation who entered Florida's public schools 1998-2009 were identified. Twenty-three SGA definitions (3rd-25th percentile) were derived. Outcomes were scores on Florida Comprehensive Assessment Test (FCAT) and students' disability classification in grades 3 through 8. A “sibling cohort” subsample included families with at least 2 siblings from the same mother in the study period. Multivariable models estimated independent relationships between SGA and outcomes.

Birth certificates for 80.2% of singleton infants were matched to Florida public school records (N = 1 254 390). Unadjusted mean FCAT scores were 0.236 SD lower among <10th percentile SGA infants compared with non-SGA infants; this difference declined to −0.086 SD after adjusting for maternal and infant characteristics. When siblings discordant in SGA status were compared within individual families, the association declined to −0.056 SD. For SGA <10th percentile infants, the observed prevalence of school-age disability was 15.0%, 7.7%, and 6.3% for unadjusted, demographics-adjusted, and sibling analyses, respectively. No inflection or discontinuity was detected across SGA definitions from 3rd to 25th percentile in either outcome, and the associations were qualitatively similar.

The associations between SGA birth and students' standardized test scores and well-being were quantitatively small but persisted through elementary and middle school. The observed deficits were largely mitigated by demographic and familial factors.