Research finds little evidence linking intrauterine growth and temperament

In contrast to earlier studies linking birth weight and temperament, Dutch researchers have found little evidence to support an association between intrauterine growth trajectories and temperamental difficulties. The experiences of the developing foetus are thought to influence the vulnerability for mental disorders, and indicators of intrauterine growth — such as low birth weight — have been linked to specific emotional and behavioural outcomes later in life. In addition, temperament has been identified as playing a role in the development and maintenance of behavioural problems in childhood and adolescence. To date, few studies have associated indicators of intrauterine growth patterns with infant or child temperaments. In the current study, the authors studied a large population-based cohort of 6-month-old infants to examine the associations between foetal growth characteristics and temperament. A total of 3,792 singleton neonates and their mothers were included in the study analysis. Size was measured at various time-points during gestation to establish growth trajectories, which were calculated on the basis of repeated measurements of foetal growth characteristics. Child temperament was assessed using an adapted version of the Infant Behaviour Questionnaire-Revised (IBQ-R) approximately 6 months after delivery. The IBQ-R obtains mothers’ ratings of specific observed behaviours. After controlling for several genetic and socioeconomic status-related factors, the results revealed that reduced foetal weight gain was positively associated with prolonged duration of orienting (where duration of orienting comprises items on attention and distractibility). Specifically, for every standard deviation decrease in total body weight gain from mid-pregnancy to birth, children scored 0.38 points higher on duration of orienting. The authors point out that while the association between foetal weight and orienting was found to be significant, most temperamental dimensions were diminished once full adjustment was made for confounding variables including national origin, maternal educational level, maternal age, and maternal height. The authors concluded that their results provided “little indication for an association between intrauterine growth and temperamental difficulties,” and suggest that associations between body size at birth and behaviour in infancy can be explained by factors influencing both foetal growth and vulnerability for temperamental difficulties. Reference Roza, S. Van Lier, P et al. 2008, ‘Intrauterine growth and infant temperamental difficulties: The generation R study’ Journal of the American Academy of Child and Adolescent Psychiatry vol. 47, pp.264—272....