Diabetes During Pregnancy Modifies the Association Between Birth Weight and Education: A Whole-of-Population Study

Higher birth weights usually reflect better intrauterine health, nutrition, and growth. Higher birth weights are also associated with better cognitive outcomes for children (1). However, among pregnancies complicated by diabetes, being born large for gestational age may reflect different intrauterine disease processes, and it is unclear whether this carries the same benefits for education. Our objective is to examine whether diabetes during pregnancy modifies the association between birth weight and school achievement.

This whole-of-population study was conducted using deidentified administrative data that linked perinatal data to children’s school assessments. School assessments were obtained from the National Assessment Program – Literacy and Numeracy (NAPLAN), which involves assessments of reading, writing, spelling, grammar, and numeracy in grade three (age ∼8 years). Scores were dichotomized at performing above the national minimum standard or not. Children who perform at or below the standard typically require classroom learning support. Z scores of birth weight for gestational age (BWGA) were calculated using Australian norms. Diabetes was recorded as either preexisting (i.e., prior to pregnancy, including all types of diabetes) or gestational diabetes mellitus. Preexisting and gestational diabetes mellitus were combined for analyses due to small numbers...