Background: Maternal obesity (defined as prepregnancy body mass index [BMI] ≥30 kg/m2) is associated with increased risk of neonatal death. Its association with infant death, postneonatal death, and cause-specific infant death is less well-characterized.
Methods: We studied the association between maternal obesity and the risk of infant death by using 1988 US National Maternal and Infant Health Survey data. A case-control analysis of 4265 infant deaths and 7293 controls was conducted using SUDAAN software. Self-reported prepregnancy BMI and weight gain were used in the primary analysis, whereas weight variables in medical records were used in a subset of 4308 women.
Results: Compared with normal weight women (prepregnancy BMI = 18.5–24.9 kg/m2) who gained 0.30 to 0.44 kg/wk during pregnancy, obese women had increased risk of neonatal death and overall infant death. For obese women who had weight gain during pregnancy of <0.15, 0.15 to 0.29, 0.30 to 0.44, and ≥0.45 kg/wk, the adjusted odds ratios of infant death were 1.75 (95% confidence interval = 1.28–2.39), 1.42 (1.07–1.89), 1.59 (1.00–2.51), and 2.87 (1.98–4.16), respectively. Nonobese women with very low weight gain during pregnancy also had a higher risk of infant death. The subset with weight information from medical records had similar results for recorded prepregnancy BMI and weight gain. Maternal obesity was associated with neonatal death from pregnancy complications or disorders relating to short gestation and unspecified low birth weight.
Conclusions: Maternal obesity is associated with increased overall risk of infant death, mainly neonatal death.
From the aDepartment of Preventive Medicine and Public Health, Creighton University School of Medicine, bDepartment of Epidemiology, College of Public Health, University of Nebraska Medical Center, Omaha, NE. cDepartment of Pediatrics, Creighton University School of Medicine, Omaha, NE; and dEpidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC.
Submitted 20 December 2007; accepted 21 July 2008; posted 23 September 2008.
W. J. R. was supported by the Intramural Research Program of the National Institutes of Health, National Institute of Environmental Health Sciences.
Correspondence: Aimin Chen, Department of Preventive Medicine and Public Health, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178. E-mail: firstname.lastname@example.org.