Can regular multivitamin/mineral supplementation modify the relation between maternal smoking and select adverse birth outcomes?

PURPOSE: The purpose of this study was to examine whether or not regular multivitamin/mineral supplementation can modify the relation between maternal smoking and preterm birth (gestational age < 37 weeks), very-low-birthweight (VLBW) (< 1500 g), moderately-low-birthweight (MLBW) (< 2499 g), or small- for-gestational-age (SGA) (< 10th percentile of birth weight for gestational age). METHODS: Live birth data from the 1988 National Maternal and Infant Health Survey (NMIHS) were used for the analysis. Maternal smoking referred to self-reported average number of cigarettes smoked after recognition of pregnancy, while regular multivitamin/mineral supplementation referred to use of multivitamin/mineral supplements for at least three days per week during the three months before and/or after recognition of pregnancy. Sample sizes included 9402 singleton infants for the analysis of preterm birth, 9395 for very or moderately low birthweight, and 9363 for small-for-gestational-age. Odds ratios were derived from logistic regression analyses after adjusting for a number of demographic and reproductive variables. RESULTS: Major results include: 1) increased risks for the adverse outcomes studied were observed among smoking women; 2) no effect of regular multivitamin/mineral supplementation in the absence of maternal smoking was revealed; and 3) relative excess risks due to interaction at different smoking levels and overall interactions between smoking and supplementation were not observed. CONCLUSIONS: These results suggest that regular multivitamin/mineral supplementation does not minimize the adverse effects associated with maternal smoking.