Table 4.

Mixed linear regression models for the mean KS decile difference between preterm and term infants

Covariate	Unadjusted		Adjusted for social factors*		Adjusted for social* and antenatal factors†		Adjusted for social*, antenatal† and intrapartum‡ factors
	Mean difference (95% CI)	P values	Mean difference (95% CI)	P values	Mean difference (95% CI)	P values	Mean difference (95% CI)	P values
Mean difference in score	−0.77 (–1.01 to −0.52)	<0.001	−0.49 (–0.80 to −0.18)	0.002	−0.59 (–0.89 to −0.13)	0.009	−0.46 (–0.84 to −0.07)	0.021
Change over four measures
Overall (KS1 to KS4)	0.10 (0.04 to 0.17)	0.001	0.10 (0.02 to 0.17)	0.017	0.10 (0.01 to 0.19)	0.035	0.10 (0.01 to 0.19)	0.035
KS1 to KS2	0.24 (–0.09 to 0.40)	0.002	0.28 (–0.08 to 0.47)	0.006	0.34 (0.10 to 0.58)	0.005	0.34 (0.10 to 0.58)	0.005
KS2 to KS3	−0.02 (–0.16 to 0.12)	0.785	−0.02 (–0.20 to 0.16)	0.830	−0.14 (–0.35 to 0.07)	0.188	−0.15 (–0.36 to 0.07)	0.182
KS3 to KS4	0.13 (–0.04 to 0.30)	0.125	0.08 (–0.14 to 0.29)	0.496	0.18 (–0.07 to 0.44)	0.166	0.19 (–0.07 to 0.45)	0.149

Measures are mean differences (95% CI) in the average KS decile and in the change seen over and between the four measures.

*Social factors: maternal age, socioeconomic group and education and ethnicity.

†Antenatal factors: gender, parity, weight, length and head circumference at birth.

‡Intrapartum factors: mode of delivery and maternal hypertension.

KS, Key Stage.