Gestational Age, Newborn Metabolic Markers and Academic Achievement

Abstract

Background: Gestational age is associated with greater school achievement and variation in newborn metabolic markers. Whether metabolic markers are related to gestational age differences in achievement is unknown. This study examines whether newborn metabolic markers are associated with gestational age differences in performance on standardized school tests.

Methods: This retrospective cohort study linked birth certificates of children born in Iowa between 2002 and 2010 to newborn screening records and school tests between 2009 and 2018. The analytical sample includes up to 229,679 children and 973,247 child-grade observations. Regression models estimate the associations between gestational age and 37 newborn metabolic markers with national percentile ranking (NPR) scores on math, reading comprehension, and science tests.

Results: An additional gestational week is associated with 0.6 (95% CI: 0.6, 0.7), 0.5 (95% CI: 0.4, 0.5), and 0.4 (95% CI: 0.4, 0.5) higher NPRs on math, reading, and science, respectively. Compared to full term children (37-44 weeks), preterm children (32-36 weeks) have 2.2 (95% CI: -2.6, -1.8), 1.5 (95% CI: -1.9, -1.1), and 1.0 (95% CI: -1.4, -0.7) lower NPRs on math, reading comprehension, and science. Very preterm children (20-31 weeks) have 8.3 (95% CI: -9.4, -7.2), 5.2 (95% CI: -6.2, -4.0), and 4.7 (95% CI: -5.6, -3.8) lower NPRs than full term children on math, reading, and science. Metabolic markers are associated with 27%, 36%, and 45% of gestational age differences in math, reading, and science scores, respectively, and over half of the difference in test scores between preterm or very preterm and full term children.

Conclusions: Newborn metabolic markers are strongly related to gestational age differences in school test scores, suggesting that early metabolic differences are important markers of long-term child development.

Keywords: gestational age; metabolic health; newborn screening; school health.

Figure 1

Differences in Test Scores by Gestational Age with and without Adjustment for Metabolic Markers. Notes: The figure reports the regression coefficients of gestational age measures in regressions of school tests scores as the dependent variables (outcomes) on gestational age and covariates. (A) is for gestational age in weeks. (B) is comparing preterm (32–36 weeks) and full term (37–44) births. (C) is comparing very preterm (20–31 weeks) and full term (37–44) births. The unit of analysis is a child-grade observation. A separate regression model is estimated for each bar using ordinary least squares. Standard errors are clustered at the child level. Academic test scores are national percentile rankings. Tests from 1st through 10th grade levels are included for school years 2009–2010 through 2017–2018. All models adjust for gender, maternal race, age, marital status, and education, as well as child’s birth year fixed effects, grade fixed effects, and school year fixed effects. Additional models adjust for metabolic markers. Sample limited to children born between 2002 and 2010.