Progress in Reducing Risky Infant Sleeping Positions -- 13 States, 1996-1997

Sudden infant death syndrome (SIDS) is one of the leading causes of postneonatal mortality in the United States (1). To reduce the risk for SIDS, the American Academy of Pediatrics (AAP) recommends that all healthy babies be placed to sleep on their backs (2). In 1994, a national "Back-to-Sleep" education campaign was begun to encourage health-care providers and the public to adopt a back or side sleeping position for all infants (3). To assess the response to these recommendations, CDC analyzed population-based data on infant sleeping positions during 1996 and 1997 from 13 states participating in the Pregnancy Risk Assessment Monitoring System (PRAMS). This report summarizes the results of that analysis and indicates that from 1996 to 1997 placement of infants in the stomach sleeping position declined significantly in four states and placement of infants in the back sleeping position increased significantly in nine states. However, the percentage of infants placed on their stomachs continued to differ by state, maternal demographics, and type of insurance coverage.

PRAMS is an ongoing, population-based surveillance system that collects information on maternal behaviors and experiences. Each month, PRAMS surveys a random sample of mothers who have given birth during the previous 2-6 months using stratified, systematic sampling of the birth certificates of infants born to state residents. Mothers are mailed a questionnaire, and follow-up mailings are sent to nonrespondents. Additional attempts to contact nonrespondents are made by telephone. Most states oversample mothers of low birthweight (less than 5 lbs, 8 oz [less than 2500 g]) infants, and four states oversample women of selected racial/ethnic groups (4).

Mothers were asked, "How do you put your new baby down to sleep most of the time?" Response categories included on the baby's side, back, or stomach. Statistical weights were applied to account for sampling probability, nonresponse, and sampling frame coverage in each state. Data from 10 states in 1996 and 13 states in 1997 were included in the analysis. The annual state-specific response rate to the entire questionnaire was approximately 70% (range: 69.4%-80.0%). Women who did not answer the sleeping position question (3.8% of all respondents) were excluded from the analysis. Because of the complex survey design, SUDAAN software was used to calculate point estimates and confidence intervals surrounding the estimates. For 1996 and 1997, data were analyzed for 15,191 and 18,701 respondents, respectively.

During 1997, the percentage of mothers who usually put their babies to sleep on their stomach varied by state (from 10.5% in Washington to 28.8% in Arkansas) (Figure 1). The prevalence of the stomach sleeping position decreased in all states from 1996 to 1997, but the percentage decline varied by state (from 7.4% in Alabama to 35.0% in Washington); significant declines (pless than 0.05) occurred in four of 10 states. In 1997, the percentage of mothers who usually put their babies to sleep on their back ranged from 32.4% in Florida to 54.7% in Colorado. The back position was the most frequently reported position in seven states. From 1996 to 1997, the prevalence of the back sleeping position increased in all states (range: 12.2%-55.5%); the increases were significant (pless than 0.05) in nine of 10 states. The prevalence of the side sleeping position ranged from 33.2% in Oklahoma to 42.6% in West Virginia in 1997 and declined in all states (percentage decline range: 3.2%-20.5%) from 1996 to 1997.

In 1997, black mothers in six of nine states were significantly more likely than were white mothers to place their babies on their stomach (risk ratio [RR]=0.99-2.13) (Table 1). Hispanic mothers were significantly less likely than were non-Hispanic mothers to put their babies to sleep on their stomach in two of five states that oversampled for race/ethnicity (RR=0.46-1.09). The decreases in the prevalence of stomach placement among American Indian/Alaska Native mothers ranged from 23.0% to 42.5%; however, rates among American Indian/Alaska Native mothers and white mothers were similar. Multiparous mothers in four of 13 states were significantly more likely to put their babies to sleep on their stomach (RR=0.93-1.47).

Reports of the stomach sleeping position were more frequent among mothers with publicly funded health insurance than among mothers with privately funded health insurance (RR=0.77-1.78). Placement on the stomach was more prevalent among mothers who breast-fed for less than 1 week than among mothers who breast-fed for greater than 1 month (RR=0.91-1.58). No consistent relation was observed between postpartum smoking and stomach placement; however, stomach placement was significantly higher among postpartum smokers in two states. Minimal differences were observed between stomach placement and education level or maternal age. Although early initiators of prenatal care were more likely to avoid using the stomach sleeping position in 11 states, the differences were not statistically significant.

Reported by: Pregnancy Risk Assessment Monitoring System Working Group. Program Svcs and Development Br and Pregnancy and Infant Health Br, Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note:

The findings in this report highlight substantial progress toward reducing the prevalence of the stomach sleeping position, an important modifiable risk factor for SIDS (5). From 1996 to 1997, respondents who reported usually placing their infants on the stomach declined across all states, with four states experiencing significant declines. As of 1997, Colorado (10.7%) and Washington nearly achieved the U.S. "Back to Sleep" campaign goal of no more than 10% of infants placed to sleep on the stomach (6). In all states, a major shift occurred to the back position. Compared with 1996 estimates from a national survey (7), PRAMS 1997 state-specific estimates of stomach placement were below the national average (24%) in eight states, and estimates for the back position were above the national average (35%) in nine states.

Despite these achievements, significant variations remain by state and by maternal characteristics in the adoption of AAP's Back to Sleep recommendation. According to a national survey, residents of states in the mid-Atlantic and southern regions were 41% and 47%, respectively, more likely than residents of other U.S. regions to place their babies on their stomachs (7). A similar pattern was observed in PRAMS states; on average, stomach placement was 10% higher in southern states than in nonsouthern states.

Black mothers were twice as likely as white mothers to place their infants on their stomachs (7-9). Excluding South Carolina, 1997 data from nine PRAMS states corroborate this association. PRAMS data and a national population-based study found a lower risk for stomach placement among Hispanics (7). The differences in placement for sleeping of infants among racial/ethnic groups may be a marker for other risk factors, such as low socioeconomic status. PRAMS data are similar to data from other studies that have shown a 50%-68% higher risk for stomach placement for multiparous mothers than for primiparous mothers (7,9,10). The relation between type of health insurance and infant sleeping position has not been examined previously, but PRAMS data suggest that stomach placement is more frequent among infants of publicly insured mothers than among privately insured mothers. Although breast-feeding and current smoking were moderately associated with stomach placement in some states, other studies have failed to identify significant associations (8,9).

The findings in this report are subject to at least five limitations. First, PRAMS does not collect information from adoptive mothers or birth mothers who put their infants up for adoption, no longer care for their infants, or are nonresidents of the states in which they gave birth. Second, misclassification of sleep position may have occurred because mothers had difficulty recalling or assigning the sleep position they used most of the time. Because the question solicits only one response, mothers who selected multiple responses to the question were not included in the analysis. Third, the survey did not include other sleep-related questions such as stability of the initial sleep position during the night and changes in position with increasing infant age. Infant age at the time of the mother's response varied by state; however, no consistent correlation existed between the state-specific percentage of infants placed on the stomach and median infant age. Fourth, comparisons of PRAMS data with that from other studies are limited by differences in study design and timing of data collection. Finally, data may not be representative of states not participating in PRAMS.

Despite these limitations, the findings in this report provide states with the information necessary to monitor their progress toward achieving the 2000 goal and to identify populations that back-to-sleep campaigns should target. In several states, mothers who smoke, who have publicly funded health insurance, who breast-fed for less than 1 week, who already have one or more children, or who are black are more likely to place their infants to sleep on their stomach than mothers without these characteristics. These findings underscore the need to develop state-specific prevention programs and back-to-sleep messages targeting subgroups of mothers at high risk for placing their babies on their stomach.

References

1. Hoyert DL, Kochanek KD, Murphy SL. Deaths: final data for 1997. Monthly vital statistics report; vol 47, no. 19. Hyattsville, Maryland: US Department of Health and Human Services, CDC, National Center for Health Statistics, 1999.
2. Task Force on Infant Positioning and SIDS. Position and sudden infant death syndrome (SIDS): update. Pediatrics 1996;98:1216-8.
3. American Academy of Pediatrics and Selected Agencies of the Federal Government. Infant sleep position and sudden infant death syndrome (SIDS) in the United States [joint commentary]. Pediatrics 1994;93:820.
4. Adams MM, Shulman HB, Bruce C, Hogue C, Brogan D. The Pregnancy Risk Assessment Monitoring System: design, questionnaire, data, and response rates. Pediatr Perinat Epidemiol 1991;5:333-46.
5. Jeffrey HE, Megevand A, Page M. Why prone sleeping position increases the risk of sudden infant death syndrome. Pediatrics 1999;104:263-9.
6. Willinger M, Hoffman HJ, Hartford RB. Infant sleep position and risk of sudden infant death syndrome: report of meeting held January 13 and 14, 1994, National Institutes of Health, Bethesda, Maryland. Pediatrics 1994;93:814-9.
7. Willinger M, Hoffman HJ, Wu KT, et al. Factors associated with the transition to nonprone sleep positions of infants in the United States: the National Infant Sleep Position Study. JAMA 1998;280:329-35.
8. Brenner RA, Simons-Morton BG, Bhaskar B, et al. Prevalence and predictors of the prone sleep position among inner-city infants. JAMA 1998;280:341-6.
9. Saraiya M, Serbanescu F, Rochat R, Berg CJ, Iyasu S, Gargiullo PM. Trends and predictors of infant sleep positions in Georgia, 1990 to 1995. Pediatrics 1998;102:1-6.
10. Lesko SM, Corwin MJ, Vezina RM, et al. Changes in sleep position during infancy: a prospective longitudinal assessment. JAMA 1998;280:336-40.

TABLE 1. Maternal characteristics associated with usually placing the infant on its stomach for sleep, by state -- selected states, Pregnancy Risk Assessment Monitoring System, 1997

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