Abstract 1052 Poster Session I, Saturday, 5/1 (poster 1)

The American Academy of Pediatrics in 1996 recommended that term and preterm infants sleep nonprone to reduce the risk for Sudden Infant Death Syndrome (SIDS). In 3 month old term infants, prone position results in more total sleep time, more quiet sleep, and fewer arousals than supine sleeping (Kahn et al., Pediatrics 1993). These findings may help explain the vulnerability for SIDS, particularly in the first 4 months of life. Our sleep studies of preterm infants at 36-38 weeks post-conceptional age have not shown significant differences in sleep organization based on body position, but there were more awakenings in supine compared to prone (Goto et al., Pediatrics in press). We have speculated that the increase in quiet sleep found in term infants may not appear developmentally until later, between 1-3 months corrected age (CA), when the risk for SIDS is greater.

The following preliminary data are from 9 former preterm infants at one month CA. The infants (mean gestational age 33.8 ± 2.5 weeks; mean birth weight 2164 ± 543g) were all recorded with time-lapsed videosomnography (TLVS) for consecutive daytime nap periods. TLVS was scored for Active Sleep (AS), Quiet Sleep (QS), and Indeterminate Sleep (IS). Paired student t-test was used for p-values. (Table) It is important to note that daytime sleep at this age was quite variable (34-115 minutes while supine; 68-139 minutes while prone), with shorter naps than those seen in infants around 36 weeks post-conceptional age (lasting 125-135 minutes on average). These older infants appropriately entered sleep in AS and the %AS was greater in prone, in contrast to the 3 month old term infant studies showing greater QS in prone. One study infant had no AS while supine, and another had no QS while supine. In comparison, both AS and QS were observed during the prone sleep of all nine infants. The %QS in both positions remained similar, consistent with our earlier preterm infant data at 36-38 weeks post-conceptional age. The significance of higher %IS in supine is unclear but may reflect increased transitions between sleep states. More subjects are needed at one month CA to fully describe sleep organization in this group. Further data are also needed at 3 months CA to compare with the full-term infant results. In conclusion, at one month CA, the duration of daytime nap sleep time is becoming more variable, and a trend of more total sleep and %AS during prone position is seen.

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This study was funded by the Child Health Research Fund at Stanford and the Perinatal Emphasis Research Center (NIH Grant HD29732).