TABLE 1

Descriptive Characteristics of the Study Population and Cognitive Scores at Age 5 and 7 Years

Variables Included in Regression Models (% of Cases Missing Data for Each Variable)Maternal Prepregnancy BMI
Underweight (BMI 16–18.5), n = 912Normal (BMI 18.5–25), n = 11 147Overweight (BMI 25–30), n = 3423Obese (BMI ≥ 30), n = 1511
Child characteristics
 Gender (0%)
  Male, %52.951.651.251.8
 Ethnicity (0.3%)
  White, %74.2a85.283.484.6
  Nonwhite, %25.8a14.716.415.4
 Mean birth weight (kg) (0.4%)3.15b3.363.46b3.49b
 Mean BMI SD score age 5 (22.2%)0.04b0.360.70b1.03b
 Mean BMI SD score age 7 (29.0%)−0.06b0.300.70b1.11b
Parental characteristics
 Mean age of mother at birth of child, y (0.04%)24.7b28.429.0b29.4b
 Maternal education (0.4%)
  Degree, %8.8a19.013.6a10.4a
  Diploma in higher education, %6.1a9.09.49.5
  A/AS/S levels, %6.5a10.29.89.6
  O level/GCSE, %49.444.648.0a50.6a
  None, %29.2a17.319.219.8
 Paternal education (11.6%)
  Degree, %10.0a18.913.3a11.1a
  Diploma in higher education, %4.8a7.77.05.9
  A/AS/S levels, %5.56.95.85.5
  O level/GCSE, %30.032.739.4a39.1a
  None, % 17.214.618.0a20.8a
 Lone parent family, %32.5a19.316.5a17.7
 Family Social Class (13.0%)
  I/II, %24.6a45.340.5a36.2a
  III, %13.013.013.513.7
  IV, %6.06.47.9a7.1
  V, %11.68.711.5a12.2a
  VI/VII, %34.9a22.823.627.7a
  VIII, %9.9a3.73.13.0
 Mean family OECD equivalized weekly income, £ (8.7%)231.8b329.4297.6b273.2b
 Maternal smoking (0.1%), %44.0a30.628.626.5a
 Maternal diabetes (0.3%), %0.71.32.3a4.8a
Children’s cognitive outcomes at age 5
 Mean nonverbal ability score (22.2%)c80.7b82.582.481.3b
 Mean verbal ability score (22.3%)d104.0b108.6107.5b107.0b
 Mean spatial ability score (22.6%)e85.6b88.587.2b85.6b
 Mean g score (22.6%)97.3b101.2100.1b98.9b
Children’s cognitive outcomes at age 7
 Mean verbal ability score (30.2%)f103.7b108.1106.0b101.5b
 Mean spatial ability score (29.6%)e114.8b117.3115.7b114.5b
 Mean number skills score (29.3%)g93.1b97.795.2b93.2b
 Mean g score, g (30.9%)98.3b101.299.6b97.8b
  • OECD, Organization for Economic Cooperation and Development.

  • a Significant difference from normal maternal BMI category by using 2-sided z tests with significance level at .05, and Bonferroni correction for multiple comparisons.

  • b Significant difference from normal maternal BMI category by using 2-sided t tests with significance level at .05, and Bonferroni correction for multiple comparisons.

  • c BAS-II picture similarities test.

  • d BAS-II naming vocabulary test.

  • e BAS-II pattern construction test.

  • f BAS-II word reading test.

  • g Number skills test adapted from NFER progress in math tests.