Racial patterns in the effects of tobacco use on fetal growth

Abstract

Objective: The aim of this study was to characterize the interaction between the effects on fetal growth of maternal smoking and race by means of race-specific growth normograms. Study Design: A case-control study was performed on white and African American mothers who were delivered at 2 hospitals in metropolitan Atlanta between February 1993 and December 1994. The study population consisted of 621 small for gestational age infants and their mothers and 324 appropriate for gestational age infants and their mothers. Face-to-face interviews with mothers and detailed anthropometric measurements of neonates were performed. Relationships among tobacco use, race, and fetal growth were evaluated by means of multiple logistic regression. The χ 2 test of trend was performed to assess a dose-response relationship between smoking and fetal growth. Results: Mothers of small for gestational age neonates were significantly more likely than control mothers to be single (52% versus 40%), to be primiparous (47% versus 37%), to have a low body mass index (26% versus 17%), to have hypertension (22% versus 15%), and to use alcohol (15% versus 9%). Mothers of small for gestational age infants were significantly more likely than control mothers to smoke (26% versus 12%) and to smoke more cigarettes ( P < .05). After controlling for potential confounders cigarette smoking in the second trimester was significantly associated with small for gestational age infants in both races (whites <1 pack/d adjusted odds ratio 3.82, 1-2 packs/d adjusted odds ratio 4.86, >2 packs/d crude odds ratio; African Americans <1 pack/d adjusted odds ratio 2.35, 1-2 packs/d adjusted odds ratio 2.52). The χ 2 test of trend results were consistent with a dose-response relationship between smoking and small for gestational age infants (whites χ 2 = 14.06, P < .0001, African Americans χ 2 = 7.99). Comparison between the 2 races of the adverse effects of smoking on fetal growth showed no significant difference. Conclusion: Self-reported maternal smoking during the second trimester is associated with fetal growth restriction in a dose-response manner. According to race-specific growth normograms no significant difference in the effects of tobacco use on fetal growth was found between white and African American women. (Am J Obstet Gynecol 1999;181:S22-S27.)