Developmental characteristics of very low-birthweight infants at 18 months' corrected age according to birthweight

Background: The objective of the present study was to describe developmental profiles of very low-birthweight (VLBW) infants compared by birthweight, because those of infants with birthweight < 750 g might be different from other VLBW infants. Methods: VLBW infants from four medical centers were followed at each site with the same protocol at 18 months' corrected age. The protocol by the Society for the Study of Follow up for High-Risk Infants, which includes a standardized developmental test, the Kyoto Scale of Psychological Development (KSPD), was used. Five hundred and sixty-four VLBW infants without neurological or neurosensory impairment were divided into four groups using 250 g birthweight intervals and outcomes were compared between the four groups. Results: Developmental characteristics of extremely low-birthweight infants (birthweight < 750 g) in comparison with other VLBW infants were as follows: (i) more infants were judged clumsy in their fine motor skills; (ii) fewer were able to speak meaningful words although they were able to understand oral simple orders; (iii) developmental quotients (DQ) of KSPD was significantly lower; and (iv) more infants were judged as hyperactive. Conclusion: Developmental profiles of VLBW infants without major handicaps at 18 months' corrected age correlated significantly with their birthweight sequence. These results provide useful information on developmental outcomes of VLBW infants.