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Table 1 Mean and standard deviation of neurodevelopment indices by infant age and participants’ characteristics (n = 343) a

From: Effect of maternal job strain during pregnancy on infant neurodevelopment by gender at 6 and 12 months: Mothers and Children’s Environmental Health (MOCEH) study

Characteristic n (%) or mean ± SD b 6 months (n = 306) 12 months (n = 252)
MDI P-value PDI P-value MDI P-value PDI P-value
Total   98.0 ± 10.9   97.0 ± 13.9   101.3 ± 15.9   94.6 ± 16.2  
Maternal age 30.1 ± 3.3         
≤30 years 208 (60.6) 98.9 ± 11.7 0.10 98.1 ± 14.1 0.08 100.5 ± 15.8 0.34 94.5 ± 15.5 0.89
>30 years 135 (39.4) 96.7 ± 9.3   95.2 ± 13.4   102.5 ± 16.1   94.8 ± 17.2  
Maternal education          
≤ High school 58 (16.9) 98.0 ± 11.0 1.00 98.5 ± 13.4 0.39 100.5 ± 14.0 0.75 95.0 ± 18.5 0.88
≥ University 285 (83.1) 98.0 ± 11.0   96.7 ± 13.9   101.4 ± 16.3   94.6 ± 15.7  
Monthly family income          
< $2,000 41 (12.0) 98.7 ± 9.2 0.78 98.7 ± 14.7 0.45 97.2 ± 17.4 0.10 96.0 ± 18.8 0.61
$2,000-$4,000 165 (48.1) 98.3 ± 11.9   97.5 ± 14.1   100.5 ± 15.2   93.7 ± 16.3  
> $4,000 137 (39.9) 97.5 ± 10.0   95.8 ± 13.2   103.7 ± 16.2   95.4 ± 15.1  
Sex          
Male 175 (51.0) 97.0 ± 10.9 0.09 94.6 ± 14.4 0.002 99.7 ± 16.5 0.11 93.4 ± 16.6 0.22
Female 168 (49.0) 99.1 ± 10.9   99.5 ± 12.9   102.9 ± 15.1   95.9 ± 15.6  
Birth Weight (kg) 3.33 ± 0.35         
Gestational age (weeks) 39.2 ± 1.0         
  1. MDI: Mental Development Index, PDI: Psychomotor Development Index.
  2. aTotal number of mother-child pairs that underwent JCQ during pregnancy for a mother and K-BSID-II at 6 or 12 months of age for a child.
  3. bValues were numbers and percentages for categorical variables and means ± SDs for continuous variables.
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