Term-gestation low birth weight and health-compromising behaviors during pregnancy.

Objective: To estimate the association between term-gestation low birth weight (term-LBW) rates and increasing numbers of health-compromising behaviors during pregnancy.

Methods: Retrospective cohort study of 78,397 term live births in Kansas City, Missouri, 1990-2002. Information on maternal and newborn characteristics was obtained form birth certificate records. Health-compromising behavior, specifically, smoking, alcohol, and drug use, was classified by the numbers and combinations of behaviors engaged in during pregnancy. Covariates included race, age, interconception interval, education, Medicaid status, medical risk factors, adequacy of prenatal care, and marital status.

Results: The cohort was 61% white, 16% less than 20 years of age, 45% on Medicaid, 24% with medical risk factor, and 45% single pregnant women. Overall term-LBW rate was 3.3%, and it increased with numbers of health-compromising behaviors: 2.6% (none), 5.5% (1), 10.8% (2), and 18.5% (3), P < .001. Unadjusted odds ratio (OR) for term-LBW increased with increasing numbers of behaviors (OR 1.0 [none]; 2.3, 95% confidence interval 2.0-2.4 [smoking]; 0.9, 0.6-1.4 [alcohol]; 2.1, 1.5-3.0 [drugs]; 4.6, 3.6-5.8 [smoking + alcohol]; 4.4, 3.6-5.4 [smoking + drugs]; 4.2, 1.5-11.9 [drugs + alcohol]; 8.4, 6.2-11.5 [smoking + alcohol + drugs]). However, on adjusting for covariates, smoking, alone (OR 2.3, 2.0-2.5) or in combinations with other behaviors (OR 4.4, 3.4-5.7 [smoking + alcohol]; 2.0, 1.6-2.6 [smoking + drugs]; and 3.3, 2.2-4.7 [smoking + alcohol + drugs]) remained the major risk factor for term-LBW.

Conclusion: Smoking alone or in combination with alcohol and/or drug use is associated with term-LBW among women who engage in health-compromising behaviors. The effect is especially pronounced when smoking is combined with alcohol consumption.