Foetal origins of adult neurocognitive performance

Foetuses are affected by being born very preterm/very low birthweight (VP/VLBW) or being born at low birthweight for gestation (SGA). Both factors have been associated with lower IQ while VP/VLBW has been associated with executive functioning performance, such as working memory, inhibitory control, and attention problems. Several questions remain: 1. Are VP/VLBW’s effects on adult IQ universal (found regardless of country or culture)? 2. Is it general cognitive functioning (IQ) or specific executive functions that explain associations of attention problems with VP/VLBW birth? 3. Are SGA’s effects on IQ apparent in early childhood but grow out of them by adulthood? Using individual level data from eight international cohorts, study 1 found that VP/VLBW adults had IQ scores 12 points lower than controls. Among VP/VLBW participants, the presence of intraventricular haemorrhage, lower birthweight for gestation, and lower maternal education were major risk factors for lower IQ. In study 2, attention differences between VP/VLBW adults and controls were investigated in two cohorts. Lower childhood IQ was consistently associated with adult attention problems. IQ explained more of the differences between VP/VLBW and controls in adulthood than any specific executive function. Study 3 investigated IQ development in the Bavarian Longitudinal Study, finding that the IQ of SGA individuals was consistently lower than those born at appropriate weight for gestation throughout the first 26 years of life. While SGA was associated with an 8 IQ point deficit, socioeconomic status and the quality of the parent infant relationship both had larger associations (14 and 10 points, respectively). Overall, VP/VLBW and SGA birth are universally associated with lower adult IQ. Additionally, VP/VLBW’s lower IQ is pervasive with further consequences for attention problems. Finally, low familial socioeconomic status has additional adverse effects on IQ and should be considered in future research and intervention for VP/VLBW or SGA children