Table 5

Mixed linear regression models for the mean KS decile difference between extreme preterm or moderate/late preterm birth and term infants

CovariateUnadjustedAdjusted for social factors*Adjusted for social* and antenatal factors†Adjusted for social*, antenatal† and intrapartum‡ factors
Mean difference (95% CI)P valuesMean difference (95% CI)P valuesMean difference (95% CI)P valuesMean difference (95% CI)P values
Extreme preterm infants
 Mean difference in score−0.70 (–1.04 to −0.37)<0.001−0.50 (–0.93 to −0.06)0.0250.45 (–0.95 to 0.05)0.080−0.40 (–0.91 to 0.11)0.122
 Changes over four measures
  Overall (KS1 to KS4)0.09 (0.01 to 0.18)0.0300.09 (−0.01 to 0.20)0.0870.11 (–0.01 to 0.23)0.0750.11 (–0.01 to 0.23)0.072
  KS1 to KS20.17 (–0.04 to 0.38)0.1210.34 (0.07 to 0.61)0.0150.50 (0.19 to 0.81)0.0020.50 (0.19 to 0.82)0.002
  KS2 to KS3−0.05 (–0.25 to 0.15)0.615−0.14 (–0.38 to 0.11)0.271−0.34 (–0.61 to −0.07)0.015−0.35 (–0.62 to −0.07)0.015
  KS3 to KS40.21 (–0.03 to 0.44)0.0810.17 (–0.13 to 0.47)0.2630.32 (–0.02 to 0.65)0.0620.33 (–0.01 to 0.67)0.060
Moderate or late preterm
 Mean difference in score−0.63 (–0.89 to −0.37)<0.001−0.42 (–0.74 to −0.10)0.011−0.47 (–0.86 to 0.09)0.016−0.42 (–0.80 to −0.03)0.036
 Changes over four measures
  Overall (KS1 to KS4)0.10 (0.03 to 0.16)0.0040.09 (0.01 to 0.17)0.0310.10 (0.01 to 0.20)0.0290.11 (0.01 to 0.20)0.028
  KS1 to KS20.25 (0.09 to 0.41)0.0030.27 (0.07 to 0.48)0.0090.34 (0.10 to 0.58)0.0060.33 (0.10 to 0.59)0.006
  KS2 to KS3−0.05 (–0.20 to 0.50)0.500−0.06 (–0.24 to 0.12)0.538−0.12 (–0.33 to 0.09)0.252−0.13 (–0.34 to 0.09)0.245
  KS3 to KS40.14 (–0.04 to 0.32)0.1210.11 (–0.12 to 0.33)0.3650.18 (–0.08 to 0.44)0.1880.18 (–0.08 to 0.45)0.169
  • 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.