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Table 3 Covariates in association with a change in intelligence quotient

From: Placental mitochondrial DNA content is associated with childhood intelligence

Covariates Multi variable model
Change in IQ 95% CI p-value
Covariates total intelligence quotient    
Girls − 2.57 − 5.32 to 0.17 0.07
Birth weight, + IQR 1.81 − 0.36 to 3.98 0.10
Gestational age, + IQR 0.17 − 1.67 to 2.00 0.86
Birth year, + 1 year − 1.99 − 3.03 to − 0.96 0.0002
Peripheral cord insertion 1.31 − 1.39 to 4.00 0.34
Age at measurement, + 1 year − 1.50 − 3.06 to 0.06 0.06
High parental educational level 6.99 4.19 to 9.79 < 0.0001
Neigbourhood household income, + IQR − 0.42 − 2.10 to 1.25 0.62
Maternal smoking during pregnancy − 1.46 − 6.21 to 3.29 0.55
Urban environment, + IQR 2.40 − 0.03 to 4.83 0.05
Covariates verbal intelligence quotient    
Girls − 3.52 − 6.24 to − 0.79 0.01
Birth weight, + IQR 1.78 − 0.37 to 3.94 0.11
Gestational age, + IQR − 0.13 − 1.88 to 1.62 0.88
Birth year, + 1 year − 2.21 − 3.15 to − 1.26 < 0.0001
Peripheral cord insertion 0.87 − 1.79 to 3.54 0.52
Age at measurement, + 1 year − 1.83 − 3.26 to − 0.40 0.01
High parental educational level 6.76 4.14 to 9.38 < 0.0001
Neigbourhood household income, + IQR − 0.98 − 2.55 to 0.58 0.22
Maternal smoking during pregnancy − 2.29 − 6.73 to 2.14 0.31
Urban environment, + IQR 1.54 − 0.77 to 3.84 0.19
Covariates performance intelligence quotient    
Girls − 1.50 − 4.48 to 1.47 0.32
Birth weight, + IQR 0.99 − 1.31 to 3.28 0.40
Gestational age, +IQR 0.51 − 1.41 to 2.43 0.60
Birth year, + 1 year − 1.18 − 2.27 to − 0.09 0.03
Peripheral cord insertion 0.56 − 2.28 to 3.39 0.70
Age at measurement, + 1 year − 0.71 − 2.35 to 0.93 0.40
High parental educational level 5.57 2.65 to 8.49 0.0003
Neigbourhood household income, + IQR 0.14 − 1.61 to 1.88 0.88
Maternal smoking during pregnancy − 0.09 − 5.04 to 4.86 0.91
Urban environment, + IQR 2.59 0.08 to 5.11 0.05
  1. CI confidence interval, IQR interquartile range