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Persistent Racial/Ethnic Disparities in Supine Sleep Positioning Among U.S. Preterm Infants


Mother watching her baby sleep.

Key takeaways

  • The study analyzed pregnancy Risk Assessment Monitoring System data from 2000 to 2015 for maternal-reported supine sleep positing (SSP) adherence for early preterm and late preterm infants by maternal race/ethnicity.

  • Non-Hispanic black infants had lower odds of SSP compared with Non-Hispanic white infants in both preterm groups.

  • Even though the odds of SSP adherence improved each year for all racial/ethnic preterm groups, the racial/ethnic disparity in SSP among preterm infants persists just as it has for healthy, full-term infants.

Research background: assessing trends in racial disparity

Sudden unexpected infant death (SUID) accounts for more than 3,500 deaths in infants under the age of 1 in the United States annually.

The specific cause of SUID is unknown, but risk factors have been identified. They include:

  • Race/ethnicity
  • Preterm birth (<37 weeks gestational age) as an independent factor
    • 2 to 3 times higher SUID rate compared to full term infants
    • Early preterm is considered <34 weeks gestational age
    • Late preterm is 34 to 36 weeks gestational age


2-3x higher SUID rate compared to full term infants.
<34 weeks gestational age is considered early preterm.
34-36 weeks gestational age is late preterm.

Previous research has shown non-Hispanic black (NHB) infants are more likely to experience SUID than non-Hispanic white (NHW) infants. NHB infants make up 15%of all U.S. births and 29%of all SUIDS, according to the latest data from the National Vital Statistics Report by the Centers for Disease Control and Prevention (CDC). In preterm NHB infants, the risk is doubled. But in contrast, Hispanic infants, when compared with NHW infants, are at lower risk for SUID (54 per 100,000 live births versus 85 per 100,00 live births, 2014-2017).

SUID risk and racial disparity in parental adherence to safe infant sleep habits has been well studied in healthy, full-term infants. One of the most effective, modifiable parental behaviors that may reduce risk of SUID is supine sleep positioning (SSP) or back sleeping adherence. This means the infant sleeps in the same room as the parent but not the same bed, on a separate, flat firm surface without elevation of the head, as well as no unsafe objects or a pacifier.

Less is known about racial/ethnic disparity in safe sleep for preterm infants, who are at greater risk for SUID. Neonatologist and safe infant sleep expert Sunah Hwang, MD, PhD, MPH/MSPH, and other researchers in the Section of Neonatology at Children’s Hospital Colorado aimed to evaluate these disparities in maternal reporting of SSP in U.S. infants born early preterm and late preterm from 2000 to 2015. They hypothesized NHB infants in the study period would have persistently lower rates of SSP compared to the NHW infants.

Research methods: reviewing 15 years of state data

The study pulled data from CDC’s national Pregnancy Risk Assessment Monitoring System (PRAMS). Fifteen states met the study inclusion requirements for 2000 to 2015.

  • The mother’s responses to the question: “In which position do you usually put your infant to sleep (side, back, and/or stomach)?”
  • CDC categorized maternal race/ethnicity as NHW, NHB and Hispanic, with “other” for any other racial group answers due to smaller group size.
  • Gestational age estimates, pregnancy and delivery information and maternal demographics came from linked birth certificates.
  • Other history was obtained from PRAMS.
  • Maternal and infant characteristics were reviewed from 2000 to 2002 and 2013 to 2015 to see if sociodemographic changes may have occurred as SSP was changing over time.

Research results: Lower odds of SSP adherence found in NHB and Hispanic mothers

There were 66,131 mothers included in the study cohort.

SSP adherence for late term and preterm babies:

  • Significant overall improvements from 2000 to 2015
  • Adjusted odds of SSP increased each year by:
    • 8.5% for early preterm (overall improvement from 56.5% to 80.7%)
    • 5.2% for late preterm (overall improvement from 61.3% to 76.8%)

SSP adherence by race/ethnicity and gestational age:

  • Odds of SSP improved in Hispanic, NHB and NHW mothers each year
  • The race-by-year interaction was not significant in either early preterm or late preterm infants
  • NHB mothers had consistently lower odds of SSP compared with NHW mothers in both age groups
  • Hispanic mothers had lower odds of SSP compared with NHW mothers in both age groups, but it was not statistically significant

Other factors associated with SSP:

  • For early preterm infants: maternal age, education, prior live birth and plurality
  • For late preterm infants: the same as early preterm with the addition of marital status
SSP adherence for late term and preterm babies: significant overall improvements from 2000 to 2015.

Research discussion and conclusion: SSP adherence increased for preterm infants but racial disparities persisted

While study authors found SSP increased for all racial/ethnic and preterm infant groups from 2000 to 2015, racial/ethnic disparities for preterm infants continued. The rate of SSP improvements also did not change among the age groups or racial/ethnic groups. Racial disparities between NHW and NHB mothers appear to remain the same as decades-old trends for disparity in infant mortality and SUID rates.

SUID rates for Hispanic infants are lower than for NHW infants, but study data shows the SSP prevalence for Hispanic infants is persistently lower than NHW infants. Authors hypothesize there are other protective factors in place in Hispanic families.

SSP prevalence among infants born early preterm was greater than those born late preterm. This could be due to likelihood of longer Neonatal Intensive Care Unit stays for early preterm infants where mothers gain more awareness, education and engagement about safe sleep practices and SUID risks.

Study authors noted efforts are needed to better understand what affects safe sleep practices in preterm infants among these families. Study authors expressed the need for more attention on the impact of racism on SUID and parental access and adoption of risk-reducing practices.

Study limitations of note include:

  • Only 16 of the 41 PRAMS states, which had less than two years of missing data, were included in the study, so results may not be nationally representative of SSP practices among preterm infants.
  • Several southern states with large NHB populations and states with larger Hispanic populations were not included in this analysis, and the racial/ethnic disparity could be even greater than the study demonstrated.

To better direct resources for effective interventions to adhere to SSP, future studies should seek to gain more understanding of the barriers or catalysts for NHB and Hispanic caregivers.