Assessment of Infant Sleeping Position -- Selected States, 1996

Sudden infant death syndrome (SIDS) is the leading cause of postneonatal mortality in the United States (1). In 1992, the American Academy of Pediatrics (AAP) recommended that all healthy babies be put to sleep either on their back or side to reduce the risk for SIDS (2). In 1994, a national "Back to Sleep" education campaign was initiated to encourage the public and health-care providers to put babies to sleep on their back or side (3). In November 1996, the AAP modified its policy to preferentially recommend putting infants on their back because of the lower risk for SIDS associated with this position relative to the side position (4). To assess adherence to recommendations for infant sleeping position, CDC analyzed population-based data on the usual infant sleeping position for 1996 births by race from 10 states participating in the Pregnancy Risk Assessment Monitoring System (PRAMS). This report summarizes the results of that analysis and indicates that infant sleeping position varied by state and race.

PRAMS is an ongoing, state-based surveillance system of maternal behaviors before, during, and after pregnancy. Each month, PRAMS surveys a random sample of mothers who have given birth during the previous 2-6 months by using stratified, systematic sampling of resident birth certificates. A questionnaire is mailed to each mother, and a second questionnaire is mailed to nonrespondents. Nonrespondents are then contacted 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 groups. Details of the survey design, questionnaire, and other operational aspects of the survey have been published (5).

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. The state-specific response rate to the entire questionnaire ranged from 71% to 80%. To account for the complex survey design, SUDAAN was used to calculate point estimates and standard errors for each sleeping position by state and maternal race/ethnicity. Women who did not answer the sleeping position question were excluded from the analysis (3.8% of all respondents). Data were analyzed for 15,195 respondents.

The percentage of respondents who reported usually putting their babies to sleep on their stomach varied by state (from 16.0% in Maine to 30.8% in Alabama) (Table_1). In five southern states, the prevalence of the stomach sleeping position was approximately twofold higher than in the states having the lowest percentages (Maine and Washington). The percentage of respondents who reported putting their babies to sleep on their back was highest in Washington (42.9%) and Alaska (40.8%) and lowest in Georgia (24.5%), Florida (25.4%), and South Carolina (25.8%). In most states, respondents usually put their babies to sleep on their side.

The percentage of black mothers who put their babies to sleep on their stomach was 11%-54% higher than that for white mothers; the percentages ranged from 22.5% in Washington to 42.1% in Florida among black mothers, and from 16.1% in Maine to 30.5% in Oklahoma among white mothers. For American Indians in two states (Washington and Oklahoma), 16.0% and 33.9% of respondents, respectively, reported usually putting their babies to sleep on their stomach. The comparable percentage for Alaska Natives was 23.5% in Alaska.

The median age of infants in Oklahoma (132 days) was at least 1 month older than that in all other states except New York (103 days) and South Carolina (117 days). Median infant age in Washington and Maine, where the prevalence of the stomach sleeping position was lowest, was 98 days and 87 days, respectively.

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

Editorial Note

Editorial Note: Usual infant sleeping position is monitored periodically to assess the success of efforts to encourage mothers and other caretakers to place babies on their back for sleeping. During 1992-1996, placement on the stomach declined from 70% to 24%, and placement on the back increased from 13% to 35% (6). In the PRAMS survey, state-specific prevalence of the stomach sleeping position in 1996 exceeded the national average in five states and was lower than the national average in four states. The variation observed among states may result from differences in infant age at the time the mother responded to the questionaire, the rate of decline since 1992, or the distribution of factors (i.e., maternal age, education, parity, and exposure to health-promotion messages) related to the choice of infant position.

Infants aged greater than or equal to 16 weeks were more likely to be placed on their stomach than were infants in younger age groups (6). However, the relation between the state percentages of babies put to sleep on their stomach and median infant age when mothers responded to the questionnaire was not always consistent. Differences in the rate of decline by state may result from variations in the intensity and effectiveness of efforts to encourage back sleeping through the "Back to Sleep" campaign and other efforts. However, differences in the rate of decline cannot be assessed because state-specific data are not available before 1996. Additional analysis is required to determine whether socioeconomic status, access to health care, or advice by health-care providers in addition to other predictors of infant position are related to the state or race differences found in this report.

The higher rate of stomach sleeping among blacks than whites is consistent with the twofold higher rate reported nationally in a previous study (22% versus 43%) (6). The rate for Alaska Natives was similar to the national average but still was higher than that for whites in Alaska. In Washington, the rate for American Indians was comparable to that for whites (16.0% and 16.7%, respectively) and is the lowest rate for any racial group in the 10 states. In comparison, in Oklahoma the rate for American Indians was the same as that for blacks (33.9%). These findings suggest that infant sleep positioning practices vary within groups of American Indians and may explain the unequal risk for SIDS found among American Indians (7).

The findings in this report are subject to at least three 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. Finally, the survey did not include other sleep-related questions such as stability of the initial sleep position during the night and changes in positioning with increasing infant age. Infant age at the time of the mother's response varied by state and may explain why some mothers whose infants were older reported using a stomach position.

Despite these limitations, the findings in this report provide useful data that states can use as a baseline to measure progress toward the national goal of the "Back to Sleep" campaign to reduce the percentage of infants put to sleep on their stomach to less than or equal to 10% by 2000 (4). The 38% decline in SIDS during 1992-1996 in the United States is associated with the substantial declines observed in the percentage of infants put to sleep on their stomach (2,8).

Innovative communication strategies and outreach programs are needed to educate all persons who care for infants, particularly blacks and certain American Indian populations, to reduce the proportion of babies placed to sleep on their stomach. These risk-reduction strategies must consider cultural and other barriers to adopting the recommended infant sleeping position and/or the appropriateness of the health-education message for high-risk groups. In designing outreach programs to promote the recommended infant sleeping position, public health officials also should consider factors that influence a caregiver's behavior, such as advice given by a health-care provider, mother's observation of a newborn's health-care provider, experience with previous children, or presence of a grandmother in the home (6,8,9). Decreasing the difference in SIDS rates in high-risk populations will require new educational efforts and the identification and modification of the risk factors that contribute to the disparity in mortality.

References

1. CDC. Sudden infant death syndrome -- United States, 1980-1994. MMWR 1996;45:859-63.

2. American Academy of Pediatrics Task Force on Infant Positioning and SIDS. Positioning and SIDS. Pediatrics 1992;89:1120-6.

3. 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, MD. Pediatrics 1994;93:814-9.

4. American Academy of Pediatrics Task Force on Infant Positioning and SIDS. Positioning and sudden infant death syndrome (SIDS): update. Pediatrics 1996;98:1216-8.

5. Adams MM, Shulman HB, Bruce C, Hogue C, Brogan D. The Pregnancy and Risk Assessment Monitoring System: design, questionnaire, data, and response rates. Pediatr Perinat Epidemiol 1991;5:333-46.

6. Willinger M, Hoffman H, Wu K, 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;280:329-39.

7. Indian Health Service. Trends in Indian health 1996. Washington, DC: US Department of Health and Human Services, Public Health Service, 1996.

8. Brenner RB, Simons-Morton BG, Bhaskar B, et al. Prevalence and predictors of prone sleep position among inner-city infants. JAMA 1998;280:341-6.

9. Lesko SM, Corwin MJ, Vezina RM, et al. Changes in sleep position during infancy: a prospective longitudinal assessment. JAMA 1998;280:336-40.

Use of trade names and commercial sources is for identification only and does not imply endorsement by CDC or the U.S. Department of Health and Human Services.

TABLE 1. Percentage distribution of usual infant sleeping position, by maternal race and state -- selected states, Pregnancy
Risk Assessment Monitoring System, 1996
==============================================================================================================================================================================================
                                                                                                                                                South
                      Alabama           Alaska           Florida          Georgia           Maine           New York         Oklahoma         Carolina        Washington       West Virginia
                      (n=1769)          (n=973)         (n=1861)          (n=1547)         (n=1143)         (n=1248)         (n=1825)         (n=1885)         (n=1532)          (n=1412)
Race/Sleeping       ------------     -------------    -------------     ------------     ------------     ------------     -------------    -------------    -------------     -------------
 position             %    (SE*)       %     (SE)       %     (SE)        %    (SE)        %    (SE)        %    (SE)        %     (SE)       %     (SE)       %     (SE)        %     (SE)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
White
 Side               42.8   (1.9)     38.9    (2.2)    44.5    (1.9)     45.8   (2.4)     46.3   (1.7)     41.5   (1.9)     34.8    (2.0)    43.2    (1.9)    40.8    (2.3)     44.2   ( 2.0)
 Back               30.0   (1.7)     43.5    (2.2)    28.2    (1.7)     27.7   (2.2)     37.6   (1.6)     35.7   (1.9)     34.7    (2.0)    27.9    (1.7)    42.5    (2.3)     35.6   ( 1.9)
 Stomach            27.2   (1.7)     17.7    (1.8)    27.3    (1.7)     26.6   (2.1)     16.1   (1.2)     22.8   (1.7)     30.5    (2.0)    28.9    (1.7)    16.7    (1.8)     20.2   ( 1.6)

Black
 Side               42.0   (2.7)         --+          43.1    (2.3)     44.7   (2.2)         --           44.7   (6.8)     45.5    (6.6)    44.0    (2.7)    40.9    (3.0)     56.5   (11.1)
 Back               19.5   (2.2)         --           14.7    (1.6)     16.5   (1.2)         --           21.5   (5.6)     20.6    (5.4)    22.5    (2.3)    36.5    (3.0)     20.4   ( 7.4)
 Stomach            38.5   (2.7)         --           42.1    (2.3)     38.8   (2.1)         --           33.9   (6.5)     33.9    (6.2)    33.5    (2.6)    22.5    (2.5)     23.0   (10.0)

Alaska Native
 Side                   --           37.3    (2.3)        --                --               --               --               --               --               --                --
 Back                   --           39.2    (2.3)        --                --               --               --               --               --               --                --
 Stomach                --           23.5    (7.6)        --                --               --               --               --               --               --                --

American Indian
 Side                   --               --               --                --               --               --           36.1    (6.1)        --           41.2    (2.4)         --
 Back                   --               --               --                --               --               --           41.5    (6.2)        --           41.9    (2.5)         --
 Stomach                --               --               --                --               --               --           33.9    (6.2)        --           16.0    (2.6)         --

All races
 Side               42.3   (1.5)     39.1    (1.7)    44.3    (1.6)     44.9   (1.7)     46.4   (1.6)     41.5   (1.8)     36.1    (1.9)    43.8    (1.6)    41.0    (2.0)     44.0   ( 1.9)
 Back               27.0   (1.4)     40.8    (1.7)    25.4    (1.4)     24.5   (1.5)     37.5   (1.1)     34.5   (1.6)     33.8    (1.8)    25.8    (1.4)    42.9    (2.0)     35.1   ( 1.8)
 Stomach            30.8   (1.4)     20.1    (1.4)    30.3    (1.4)     30.6   (1.6)     16.0   (1.2)     24.0   (1.6)     30.2    (1.8)    30.4    (1.4)    16.2    (1.5)     20.8   ( 1.5)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
*  Standard error.
+  Sample size too small for meaningful analysis.
==============================================================================================================================================================================================

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