American Journal of Epidemiology Advance Access published online on September 18, 2008
American Journal of Epidemiology, doi:10.1093/aje/kwn223
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Original Contribution |
Dose-Response Associations Between Maternal Smoking During Pregnancy and Subsequent Childhood Obesity: Effect Modification by Maternal Race/Ethnicity in a Low-Income US Cohort
Correspondence to Dr. Andrea J. Sharma, Centers for Disease Control and Prevention, 4770 Buford Highway, Mailstop K-25, Atlanta, GA 30341-3724 (e-mail: AJSharma{at}cdc.gov).
Received for publication December 14, 2007. Accepted for publication June 26, 2008.
Studies suggest that children exposed to cigarette smoke in utero are at risk of becoming obese. Few researchers have evaluated the dose-response association between maternal smoking during pregnancy and childhood obesity or whether this association varies by maternal race/ethnicity. The authors obtained retrospective cohort data by linking records from the Pregnancy Nutrition Surveillance System and the Pediatric Nutrition Surveillance System on 155,411 low-income children born during 1995–2001 in 9 US states and 2 tribal nations. The authors examined maternal smoking status, duration of smoking, quantity of smoking, and both duration and quantity combined. Childhood obesity was based on a body mass index greater than or equal to the 95th percentile for sex and age, assessed at age 2–4 years. Maternal race/ethnicity modified the association between smoking during pregnancy and childhood obesity. Among non-Hispanic White mothers, both duration and quantity of smoking were positively associated with childhood obesity in a dose-response manner. Among non-Hispanic Black mothers, only heavy smoking was positively associated with childhood obesity. Among Hispanics, American Indians/Alaska Natives, and Asians/Pacific Islanders, smoking was not associated with childhood obesity. The inconsistent association between smoking during pregnancy and childhood obesity across race/ethnicity categories merits further investigation into potential explanations for this variation, which may include confounding, reporting bias, or unexplored biologic mechanisms.
child; ethnic groups; obesity; pregnancy; prenatal exposure delayed effects; smoking
Abbreviations: BMI, body mass index; PedNSS, Pediatric Nutrition Surveillance System; PNSS, Pregnancy Nutrition Surveillance System; WIC, Special Supplemental Nutrition Program for Women, Infants, and Children