Race differences in the proportion of low birth weight attributable to maternal cigarette smoking in a low-income population.

PURPOSE

To quantify race differences in the public health impact of maternal cigarette smoking on infant birth weight and to estimate the proportion of low birth weight births that could be prevented by maternal smoking cessation.

DESIGN

A cohort that consisted of 77,751 mother-infant pairs was evaluated retrospectively.

SETTING

Statewide study of Women, Infants and Children participants in North Carolina.

SUBJECTS

African-American and non-Hispanic white women who delivered a single live infant during 1988, 1989, or 1990.

MEASURES

Logistic regression estimates of the relative risk of low birth weight births for smokers were used to calculate adjusted population attributable risk percentages for smoking. Separate population attributable risk percentages were calculated for total low birth weight, moderately low birth weight, and very low birth weight, and all estimates were adjusted for prepregnancy body mass index, gestational weight gain, age, education, parity, and timing of entry into prenatal care.

RESULTS

Non-Hispanic whites had a much higher prevalence of smoking and were heavier smokers than African-Americans. For both moderately low birth weight and very low birth weight, the population attributable risk percentages for smoking were twice as high for non-Hispanic whites than for African-Americans. Overall, after adjustment, 30.7% of low birth weight births among non-Hispanic whites and 14.4% of low birth weight births among African-Americans were attributable to smoking.

CONCLUSIONS

Although the public health impact of maternal cigarette smoking on infant birth weight was twice as high for non-Hispanic whites as for African-Americans in this low-income population, smoking cessation by all low-income pregnant women would result in significant improvements in infant health and well-being.