Prenatal and early childhood predictors of intelligence quotient (IQ) in 7-year-old Danish children from the Odense Child Cohort.

Background: Cognitive development measured as intelligence quotient can predict socioeconomic markers in adulthood. It is therefore of interest to determine predictors of childhood intelligence quotient.
Aim: To assess intelligence quotient scores based on standardised Danish age-appropriate scores and to evaluate potential predictors of intelligence quotient.
Materials: At 7 years of age children in the Odense Child Cohort completed an abbreviated version of the Wechsler intelligence scale for children 5th edition consisting of four subtests (vocabulary, similarities, block design and matrix reasoning) from which the full scale intelligence quotient and verbal comprehension index were estimated. Potential predictors from pregnancy through childhood were collected from questionnaires, birth records and clinical examinations.
Methods: Intelligence quotient scores were investigated through descriptive statistics and linear regression models.
Results: The mean full scale intelligence quotient among 1375 children was 99.1 (95% confidence interval 98.5; 99.8) points. Higher full scale intelligence quotient scores were observed in girls 100.8 (95% confidence interval 100.0; 101.8) compared to boys 97.6 (96.7; 98.4), and in children of mothers with high and intermediate education 101.7 (100.4; 103.1) and 99.6 (98.7; 100.5), respectively, compared to low education 96.1 (94.9; 97.3). In linear regression analyses, longer maternal education and child sex (girls) remained strong predictors of intelligence quotient at age 7 years. In addition, paternal education, child head circumference and longer duration of breastfeeding were associated with higher intelligence quotient, whereas maternal overweight and obesity before pregnancy was associated with lower intelligence quotient.
Conclusions: Mean intelligence quotient scores were comparable to the standardised mean intelligence quotient of 100 point of Danish peers. It is important to follow up these children to determine which predictors persist into adulthood.