Page 19 - Sample Moderate prematurity, socioeconomic status, and neurodevelopment in early childhood

level technical and vocational training (12 to 16 years of education), and university or
high-level technical and vocational training (> 16 years of education). Furthermore,
parents were asked to give an indication of their net monthly household income in
euros: ≤ €850 ($1,087), €851 to €1150 ($1,088 to $1,471), €1151 to €1750 ($1,472 to
$2,239), €1751 to €3050 ($2,240 to $3,902), €3051 to €3500 ($3,903 to $4,477), and
> €3500 ($4,477). Data on occupational level were collected retrospectively from 2 medical records kept by the PCH centers. We classified the occupational level of both
parents according to the International Standard Classification of Occupations.14 We assessed the composite SES score on the basis of five indicators: educational level of father, educational level of mother, family income, occupational level of father, and occupational level of mother. Information on each of the five indicators was available for 95%, 98%, 76%, 81%, and 71%, respectively, of the children participating in this study. We standardized each of the indicators and computed the mean per child of the indicators that were available for that child, resulting in one single SES score for each child. Then the SES scores were again standardized, i.e. had a mean of 0 and an standard deviation of 1.
Developmental outcomes
Developmental outcomes were measured using the Dutch version of the 48-month form of the Ages and Stages Questionnaire (ASQ), which is a validated, parent-completed, developmental screening instrument.15,16 We computed five developmental domains of the ASQ: fine motor, gross motor, communication, problem-solving, and personal-social skills.16 Each domain consists of six questions on developmental milestones. For example, the domain communication problems consists of questions about the notion of categories, interpretation, meaning of objects, word conjugations, operating instructions, and the ability to form full sentences. Parents were asked to evaluate whether their child had achieved a milestone (yes, ten points), had partly achieved a milestone (sometimes, five points), or had not yet achieved a milestone (no, zero points). Furthermore, we computed the ASQ total score by taking the mean of the five domain scores. For the total score and the domains scores cut-offs for normal and abnormal scores were set at two standard deviations below the mean score of the Dutch reference group.15 In > 95% of cases, the mother filled out the questionnaire.
Developmental outcomes: risks multiply
29