Professor Rutgers Robert Wood Johnson Medical School New Brunswick, New Jersey, United States
Background: In the United States, nearly 3700 infants die annually from Sudden Unexpected Infant Death (SUID). SUID consists of Sudden Infant Death Syndrome (SIDS), ill-defined and unspecified causes of mortality, and Accidental Suffocation and Strangulation in Bed (ASSB). In the past decade, maternal smoking and SUID have been the focus of investigations, leading to the conclusion that maternal smoking increases SUID risk in a dose-dependent manner. Risk is also modified by the timing of exposure. There is racial disparity in smoking rates and smoke exposure, yet the impact of smoke exposure on SUID rates relative to race-specific exposure patterns has not been examined.
Objective: This investigation aimed to determine if the association between maternal smoking and SUID risk differs by race.
Design/Methods: We accessed linked infant birth and death certificate period files for 2012 and 2013 from the National Center for Health Statistics (NCHS) website, limiting the sample to births with gestational age between 24 and 42 completed weeks and birth weight between 400 and 6,000 grams. We recorded the smoking status of white non-Hispanic (WNH) and black non-Hispanic (BNH) populations and divided the observations into smoking State 1 (SS1) No Smoking, SS2 Smoked Pre-pregnancy Only, SS3 Smoked Pre- & 1st Trimester, SS4 Smoked Pre- 1st & 2nd Trimester, SS5 Smoked at all 4 periods, and SS6 Smoked on-and-off. We investigated the distribution of demographic characteristics and odds ratios for risk status in each SS category.
Results: Among SUID deaths with an overall death rate of 0.66 per 1,000 live births, 62.7% were WNH with a rate of 0.58 per 1,000 live births and 37.3% BNH with a rate of 1.30 per 1,000 live births. Race-specific odds ratios for SUID by the timing of maternal smoking (compared to the no-smoking group) and race are shown in the Table. Conclusion(s): In both WNH and BNH infants, there is a dose-dependent relationship between smoking and SUID. However, incremental exposure increases the odds ratio more in WNH infants. This observation may be due to the higher SUID rate (per 1,000 live births) among nonsmoking BNH compared to nonsmoking WNH infants (1.07 vs. 0.34, respectively), suggesting that BNH infants have more risk factors and demonstrates the unique contribution smoking makes to risk for each group.
Table 1. Odds Ratios (95% Confidence Intervals) for SUID by Maternal Smoking During Pregnancy and Race
Authors/Institutions: Thomas Hegyi, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States; Ofira Schwartz-Soicher, Princeton University, Princeton, New Jersey, United States; Nancy E. Reichman, Rutgers University--Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States; Barbara Ostfeld, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey, United States
