Objectives. To describe sleep positions among low birth weight infants, variations in sleep position according to birth weight, and changes in sleep position over time. To analyze risk factors and influences associated with prone sleep.
Design. Prospective cohort study.
Setting. Massachusetts and Ohio, 1995–1998.
Study Participants. Mothers of 907 low birth weight infants.
Results. At 1, 3, and 6 months after hospital discharge, the prevalence of prone sleeping was 15.5%, 26.8%, and 28.3%, respectively. The corresponding rates for supine sleeping were 23.8%, 37.9%, and 50.2% and for side sleeping were 57.3%, 32.4%, and 20.6%. Very low birth weight (VLBW) infants (<1500 g) were most likely to be placed in the prone position. From 1995 through 1998, prone sleeping 1 month after hospital discharge declined among all low birth weight infants from 19.9% to 11.4%; among VLBW infants, the decline in prone sleeping was replaced almost entirely by an increase in side sleeping, whereas in larger low birth weight infants, it was replaced primarily by supine sleeping. Among mothers who placed their infants to sleep in nonprone positions, professional medical advice was cited most frequently as the most influential reason, whereas among mothers of prone-sleeping infants, the infant’s preference was cited most frequently. However, mothers of prone-sleeping VLBW infants also frequently cited the influence of medical professionals and nursery practices as most important in the choice of sleeping position. The factors most strongly associated with prone sleeping were single marital status (odds ratio [OR]: 3.0; 95% confidence interval [CI]: 1.5–6.2), black race (OR: 2.6; 95% CI: 1.5–4.5), birth weight <1500 g (OR: 2.4; 95% CI: 1.3–4.3), and multiparity (OR: 2.1, 95% CI: 1.2–3.5).
Conclusions. Prone sleep decreased among low birth weight infants from 1995 to 1998. However, VLBW infants, who are at very high risk for sudden infant death syndrome, are more likely to sleep prone than larger low birth weight infants.