Socioeconomic inequalities in infant temperament: the generation R study.
BACKGROUND
A low socioeconomic status (SES) has consistently been associated with behavioural problems during childhood. The studies of SES and behaviour in infants used temperament as a behavioural measure. However, these studies in younger children yielded inconsistent findings. Furthermore, they generally did not examine explanatory mechanisms underlying the association between SES and temperament. We investigated the association between SES and temperament in infancy.


METHODS
The study was embedded in the Generation R study, a population-based cohort in The Netherlands. Maternal and paternal education, family income, and maternal occupational status were used as indicators of SES. At the age of 6 months, 4,055 mothers filled out six scales of the Infant Behaviour Questionnaire-Revised.


RESULTS
Lower SES was associated with more difficult infant temperament as measured by five of the six temperament dimensions (e.g. Fear: unadjusted z-score difference between lowest and highest education: 0.57 (95%CI: 0.43, 0.71)). Only the direction of the association between SES and Sadness was reversed. The effect of SES on Distress to Limitations, Recovery from Distress, and Duration of Orienting scores was largely explained by family stress and maternal psychological well-being. These covariates could not explain the higher levels of Activity and Fear nor the lower Sadness scores of infants from low SES groups.


CONCLUSIONS
SES inequalities in temperament were already present in six months old infants and could partially be explained by family stress and maternal psychological well-being. The results imply that socioeconomic inequalities in mental health in adults may have their origin early in life.
Jansen
Pauline W
PW
The Generation R Study Group, Erasmus MC-University Medical Centre Rotterdam, Rotterdam, The Netherlands.
Raat
Hein
H
Mackenbach
Johan P
JP
Jaddoe
Vincent W V
VW
Hofman
Albert
A
Verhulst
Frank C
FC
Tiemeier
Henning
H
D000223:Adaptation, Psychological; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D015897:Comorbidity; D004522:Educational Status; D004651:Employment / Q000706:statistics & numerical data; D005220:Fathers / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D007223:Infant; D018730:Infant Behavior; D008297:Male; D008393:Marriage / Q000706:statistics & numerical data; D001523:Mental Disorders / Q000453:epidemiology; D009035:Mothers / Q000706:statistics & numerical data; D009426:Netherlands / Q000453:epidemiology; D012649:Self Concept; D012959:Socioeconomic Factors; D013315:Stress, Psychological / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013694:Temperament