[Smoking prevalence in the 1982 birth cohort: from adolescence to adult life, Pelotas, Southern Brazil].

Objective: To assess smoking prevalence in adolescents and young adults of a population-based birth cohort.
Methods: Prospective birth cohort study of infants born in 1982, in the city of Pelotas, Southern Brazil, and interviewed in 1997, 2000-2001 and 2005. In the 1997 and 2000-2001 follow-up visits, the outcome studied was smoking, defined as the consumption of at least one cigarette in the previous week. In the 2005 follow-up visit, the dependent variable was current smoking. Adjusted analysis was performed using Poisson regression.
Results: Smoking prevalences among males were 5.9%, 20.2% and 27.6% in the 1997, 2000-2001 and 2005 follow-up visits, respectively. Among females, respective values were 9.3%, 27.5% and 23.6%. Mean age of smoking onset was 15.1 years (SD=2.5). In the multivariate analysis, lower maternal level of education, low income level in 1982, poverty during the follow-up period and maternal smoking were significantly associated with higher smoking prevalences in both sexes. Being non-white was associated with higher risk of smoking among females exclusively. Breastfeeding was not associated with smoking. Among females, smoking was inversely associated with birth weight in the crude analysis, but lost its significance in the adjusted analysis.
Conclusions: Higher incidence of smoking in poorer groups suggests that behavior such as avoiding smoking during pregnancy and increasing cigarette prices can have an important population impact.