The AAP continues to recommend avoidance of the prone sleep position to reduce the risk of SIDS. To evaluate compliance with this recommendation over time among families of at-risk and healthy term (HT) infants, we determined sleep position by interview among 630 enrollees in the Collaborative Home Infant Monitoring Evaluation (CHIME) at 5 sites across the USA from 5/1/94-4/30/96. Of these, 503 (89 SIDS siblings (SS), 88 apnea of infancy(AOI), 264 preterm (PT) infants ≤ 34 wks, 62 HT) completed the first follow up visit (≈30 days after enrollment). To determine adherence over time, we examined a subset of 208 infants (51 SS, 28 AOI, and 99 PT, 30 HT) who completed a minimum of 4 follow-up visits at the following postconceptional ages (mean wks ± SD): 44 ± 4, 49 ± 4, 56 ± 5, 71± 15. Table

Table 1

Among the 503 infants, <20% assumed the prone position at the first follow-up visit. Differences in the incidence of prone sleep position over time between at risk groups and healthy terms were not significant(Generalized Estimating Equations). Although the selection of prone sleep position has substantially decreased in the past 5 years (70% in 1992), these values remain above those from countries with aggressive Back-to Sleep campaigns. Further efforts will be necessary to reduce the incidence of prone sleeping in the United States. Supported by NICHD Grant # HD28971, 29073, 29060, 29067, 29071, 34625, 29056.