Intellectual and psychological performance in males born small for gestational age with and without catch-up growth

Infants born small for gestational age (SGA) have an increased risk of neur ologic and intellectual dysfunction. Most of these infants catch up in grow th and attain normal height, although some do not. Whether catch-up growth influences intellectual function is not known. To analyze whether intellect ual and psychological performance of males in early adulthood are associate d with body size at birth or by catch-up growth in height among bays, a pop ulation-based cohort was studied. This cohort included all male singletons born without congenital malformations in Sweden from 1973 to 1978 and alive at 18 y (n = 276,033). Information from the Swedish Birth Register was ind ividually linked to the Swedish Conscript Register. Of 254,426 conscripted males, information on intellectual and psychological performance was availa ble for 97% and 91%, respectively. Low birth weight, short birth length, sm all head circumference at birth, and preterm birth increased the risk of su bnormal intellectual and psychological performance. Among SGA-born males, t he most important predictor was the absence of catch-up growth. Being born SGA is associated with increased risk of subnormal intellectual and psychol ogical performance. The data strongly support the view that, for males born SGA, it is an advantage to have catch-up growth in length.