Table 2.

Comparison of Extremely Preterm and Normal Birth Weight Groups on Measures of Achievement and Learning

	EP Group		NBW Group		F (df) from	95% CI
Domain/Measure	n	Adj M (se)	n	Adj M (se)	ANCOVA for difference
Written language:
Letter/Word Identification	142	106.07 (1.13)	111	110.05 (1.28)	5.43 (1,248)	0.61, 7.33
Spelling	140	92.09 (1.33)	111	100.61 (1.49)	18.12 (1,246)	4.58, 12.46**b
Sum of teacher ratings of learning progress in written language	110	6.74 (0.26)	106	8.94 (0.27)	34.19 (1,211)	1.45, 2.93**ab
Mathematics:
Calculation	69	102.40 (1.19)	88	105.46 (1.05)	3.72 (1,152)	−0.07, 6.19b
Applied Problems	140	95.10 (1.44)	111	106.12 (1.61)	26.95 (1,246)	6.76, 15.28**ab
Sum of teacher ratings of learning progress in mathematics	110	4.95 (0.13)	106	5.83 (0.14)	21.42 (1,211)	0.51, 1.27**ab

Abbreviations: EP = extremely preterm; NBW = term-born normal birth weight; 95% CI = 95% confidence interval for difference (adjusted mean for NBW – adjusted mean for EP); Adj M (se) = adjusted mean (standard error); ANCOVA = analyses of covariance, adjusted for socioeconomic status, ethnicity, and sex.

Note: Achievement tests are from the Woodcock Johnson Tests of Achievement, 3^rd Edition.⁴⁹ Scores reported are grade standardized to take into account the time of year when testing occurred. With exception of Calculation, on which many children were untestable, lack of child cooperation accounted for reduced sample size on the achievement tests. Reduced sample sizes for the teacher ratings were related to the procedure of collecting ratings only from teachers of regular classrooms and a small number of teacher or school refusals.

^aSignificant when excluding children with neurosensory disorders and/or a Brief Intelligence Assessment (BIA) <85 on the Woodcock Johnson Tests of Cognitive Abilities, 3^rd Edition.⁵⁰

^bSignificant when excluding children with individual educational plans.

^**Bonferroni – adjusted p<.01.