# Table 1 Sample mean values for main control variables in LSAC B cohort.

Mode of birth p-value of diff.a
Cesarean s.e. Vaginal s.e.
(n=1,080)   (n=2,586)
Dependent variables b
Survey-based measures
School preparedness (WAI), 4–5 65.3 5.9 65.8 6.0 [0.112]
Vocabulary (PPVT), 4–5 65.4 8.8 65.3 8.4 [0.784]
Vocabulary (PPVT), 6–7 74.8 5.1 74.5 5.0 [0.134]
Vocabulary (PPVT), 8–9 79.5 4.6 79.3 4.9 [0.143]
Problem solving (MR), 6–7 10.8 3.1 10.8 3.0 [0.601]
Problem solving (MR), 8–9 10.5 2.9 10.6 3.0 [0.673]
Numeracy 409.2 72.9 412.0 74.8 [0.359]
Reading 436.3 90.5 439.4 90.0 [0.395]
Writing 423.2 62.0 425.7 59.5 [0.313]
Spelling 419.4 78.4 420.9 77.9 [0.641]
Grammar 438.8 96.9 441.6 91.9 [0.481]
Controls c
Family characteristics (socio-economic status (SES)) in year of birth
Maternal age at birth 31.752 4.810 30.438 5.159 [0.000]
Maternal age at birth squared 1031 307 953 313 [0.000]
Three or more older siblings 0.041 0.198 0.073 0.261 [0.000]
Female child 0.457 0.498 0.500 0.500 [0.019]
Either parent was born in a disadvantaged countryd 0.046 0.210 0.071 0.257 [0.002]
Mother is single 0.051 0.220 0.068 0.252 [0.040]
Mother is not legally married to partner 0.804 0.397 0.769 0.421 [0.018]
Mother was employed 0.532 0.499 0.532 0.499 [0.969]
Mother’s highest qualification
High school diploma or belowe 0.256 0.436 0.292 0.455 [0.022]
Vocational education qualificationf 0.261 0.439 0.263 0.441 [0.889]
College (bachelor) degree or above 0.483 0.500 0.444 0.497 [0.031]
Private health insurance 0.591 0.492 0.488 0.500 [0.000]
Perinatal risk factors (PN)
Low birthweight (<2.5 kg) 0.066 0.248 0.034 0.181 [0.000]
IVF treatment used 0.085 0.279 0.052 0.222 [0.000]
Multiple births 0.064 0.245 0.017 0.128 [0.000]
Head circumference of child (Z-score)g −0.262 1.119 −0.326 0.871 [0.090]
Length of baby when born (Z-score)g 0.054 1.382 0.377 0.988 [0.000]
Blood pressure medication during pregnancy 0.030 0.170 0.016 0.126 [0.020]
Diabetes medication during pregnancy 0.021 0.144 0.006 0.076 [0.001]
Antibiotic medication during pregnancy 0.108 0.311 0.098 0.297 [0.345]
Weeks of gestation 38.563 2.084 39.462 1.695 [0.000]
State of residence
New South Wales 0.279 0.449 0.320 0.466 [0.013]
Victoria and Australian Capital Territory 0.281 0.450 0.272 0.445 [0.553]
Western Australia 0.117 0.321 0.097 0.297 [0.091]
Queensland 0.212 0.409 0.200 0.400 [0.411]
South Australia 0.076 0.265 0.071 0.256 [0.588]
Northern Territory 0.009 0.096 0.018 0.132 [0.029]
Tasmania 0.026 0.159 0.022 0.148 [0.536]
Outside metropolitan areas 0.348 0.477 0.375 0.484 [0.121]
1. aThe p-values are associated with a t-test for differences in mean values between cesarean and vaginally born children. bThe descriptive results above are age-normalised, but unstandardized to give the reader a fuller picture of the data. In the regression analysis, all cognitive performance measures are age-normalised and standardised with respect to the weighted sample mean and standard deviation. cAll control variables are taken from wave 1 of the data (2004) when children are 0–1 year of age. dDisadvantaged countries are those identified by the Australian Bureau of Statistics Standard Australian Classification of Counties (2011), ABS cat. no. 1269.0. eHigh school diploma includes vocational equivalent — International Standard Classification of Education (ISCED) 1997 level 3 C. fVocational education qualification is ISCED 1997 level 4B and 5 A. gZ-scores are based on Centre for Disease Control and Prevention (CDC) growth charts and are age and gender-adjusted.