The Bayley Scales of Infant and Toddler Development in Extremely Low Birth Weight Survivors at 18 Months Corrected Age

Abstract

Background: The Bayley Scales of Infant and Toddler Development 3rd edition (Bayley-III) introduced new composite scores (Cognitive, Language and Motor scales) with subtest scores for Receptive (RC) and Expressive Communication (EC) and Fine (FM) and Gross motor (GM). The Bayley 1st (1969) and 2nd Ed. (1993) results are expressed as a Mental (MDI) and a Psychomotor Development Index (PDI). Objective: Describe Bayley-III, Bayley-II and Bayley-I results on a cohort of extremely low birth weight (ELBW) (<800 gram birth weight) children seen at 18 months corrected age. Design/Methods: Non-impaired toddlers free of severe cerebral palsy (CP), visual impairment (VI) and able to complete test items and score 50 (low score) seen in a Neonatal Follow-Up Program between 1984- 2009 were included. Bayley-I was used 1984-1993, Bayley-II 1994-2006, Bayley-III Mar 2006-Sept 2009. Paired T-tests were used to compare Bayley-III profiles. Results: Results of Bayley Assessments Bayley Version Median MDI (Range) Median PDI (Range) Median Cognitive (Range) Median Language (Range) Median RC /EC Median Motor (Range) Median FM/ GM During period 1 (1984-1993) there were 201 subjects: 22 were excluded (14 CP, 12 VI, 10 low score). Included subjects (n=179) had a median birth weight (bwt) of 720 g (range 480-800 g) and median gestational age (GA) of 25.7 weeks (range 23-33). Period 2 (1994-2006) had 203 subjects: 40 excluded (8 CP, 11 VI, 24 low score) leaving 163 with a median bwt of 700 g (425-800 g) and GA 25.7 wks (range 22-32). Period 3 (2006-2009) had 98 subjects: 6 excluded (5 CP, 3 VI, 1 low score) leaving 92 with a median bwt of 658 g (range 385-800 g) and GA 25 wks (range 23-29). Bayley-III Cognitive scores were higher than Language and FM > GM (both p < 0.0001). RC=EC. Conclusions: In ELBW subjects, Bayley-I MDI and PDI scores are higher than Bayley-II scores consistent with the literature. The Bayley-III profile of Canadian non-impaired ELBW infants show better cognitive vs language and better fine vs gross motor skills. Several studies have shown worse cognitive outcomes in ELBW than term control subjects so the median cognitive score of 100 highlights that results should be verified against Canadian term controls.