Antenatal and postnatal growth and 5-year cognitive outcome in very preterm infants

Abstract

Objectives: To study how antenatal growth affects cognitive outcome in very preterm infants and to determine whether there is an association between growth in any particular time period between birth and 5 years of age and cognitive outcome. Small for gestational age (SGA) and non-SGA infants were analyzed separately, because antenatal growth may affect postnatal growth.

Methods: Very low birth weight (<1501 g) infants born between 2001 and 2006 and infants born at <32 gestational weeks between 2004 and 2006 who were treated at Turku University Hospital (n = 181) were followed. Weight, length, and head circumference (HC) of the infants were measured at 9 time points between birth and 5 years. The growth was determined as a z score change between measurement points. Cognitive development was assessed at 5 years of age with the Wechsler Preschool and Primary Scales of Intelligence-Revised. The association between growth and full-scale IQ (FSIQ) was studied.

Results: Growth in length and height was not associated with 5-year cognitive outcome. However, weight (r = 0.18, P = .04) and HC growth (r = 0.25, P = .01) between birth and 2 years of corrected age correlated to FSIQ in non-SGA children. In SGA children, HC growth (r = 0.33, P = .03) around term age correlated to FSIQ.

Conclusions: Cognitive outcome was similar in SGA and non-SGA very preterm infants. Growth affected cognition positively in both subgroups, but the critical time period was different.

Keywords: cognitive development; growth; preterm infants.