[The association of gestational duration and birth weight with child IQ: The Generation R Study]

Several psychiatric disorders are considered to be neurodevelopmental in origin. Population-based research provides us with a unique opportunity to explore how prenatal factors influence neurodevelopment.To analyse whether non-verbal child iq is linked to gestational duration and birth weight and to find out whether these birth factors can be seen as to reflect the intra-uterine environment.Participants were 5,893 (73.6%) children enrolled in the Generation R Study. The gestational duration was determined on the basis of foetal ultrasound scans. Birth weight was measured and transformed into standard deviation scores corrected for gestational duration and gender. The non-verbal iq was measured when the child reached the age of six.Even during in the a-term period, gestational duration showed a linear association with non-verbal iq, whereas the association between birth weight and non-verbal iq was found to be curvilinear.Independently and showing different patterns, both gestational duration and birth weight were found to have a predictive value for childhood non-verbal iq. This finding illustrates the various mechanisms that could lead to neurodevelopmental disorders.