Abstract 1461 Poster Session II, Sunday, 5/2 (poster 23)

A number of studies have suggested that intrauterine drug exposure is associated with altered neurologic or motor function. The purpose of this study was to assess the association between patterns of motor development over the first 18 months, and exposure status in infants enrolled in the multisite longitudinal MLS Study (Brown University; University of Miami; University of Tennessee, Memphis; Wayne State University). 1388 infants (11% <1500 gm at birth), group matched for gestational age, race and gender, were enrolled (658 exposed [EXP] to cocaine/opiates and 730 comparison [COMP]). Alcohol, marijuana, and tobacco exposure occurred in both groups. Measures were administered by masked certified examiners, including the NICU Network Neurobehavioral Scale (NINNS) at 1 mo corrected age; the Posture and Fine Motor Assessment of Infants (PFMAI) at 4 mo; the Bayley Psychomotor Index (PDI) at 12 mo; and the Peabody Motor Scales (PMS) at 18 mo. Motor scores from each measures were converted to standard (Z) scores; scores for each infant were averaged; a slope of the 4 averaged Z scores was computed for each infant; and mean slopes for EXP and COMP infants were compared (t test). Regression analysis was performed adjusting for birth weight, exposure to alcohol, marijuana, tobacco, opiates, and social class (Hollingshead). Cluster analysis was used to identify subgroups of infants with specific patterns of motor development across the four motor exams. 605 infants had complete motor data (263 EXP, 342 COMP). On the standardized measures, the mean PDI was 91; the mean was 95 for gross motor and 87 for fine motor on the PMI. There was no significant difference between the mean slopes of the EXP and COMP infants by t test. Cluster analysis identified a group of infants (n=60) characterized by motor scores which were significantly below the mean: > 1.7 SD on the NNNS, ≥.66 SD on the PDI, and ≥.49 SD on the PMS. EXP infants were more likely than COMP to show this pattern of low motor scores (60 vs. 40%, Chi Sq.=7.4; p<.03). Regression analysis revealed that this effect was due to poly-substance abuse (alcohol, marijuana, tobacco and opiates) rather than to cocaine alone, and was independent of SES (p<.05). We conclude that, although the trajectory of motor development is similar between EXP and COMP infants, there is a subgroup of poly-substance exposed infants with consistently poor motor function at 1, 12, and 18 mo. The finding that the mean motor score of both groups is below the norm, especially for fine motor at 18 mo, is consistent with other studies of children growing up in underprivileged environments.