Smoking and trajectories of dysmenorrhoea among young Australian women.

Objective To investigate the association of cigarette smoking at baseline and trajectories of dysmenorrhoea in a large sample of Australian women. Design A prospective cohort study. Setting Australian (population-based survey). Participants A total of 9067 young women, with at least three measures of dysmenorrhoea, randomly sampled from the national Medicare database and followed up from 2000 to 2012. Main outcome measures Trajectories of dysmenorrhoea. Results At baseline, approximately 25% reported dysmenorrhoea and 26% were current smokers. Four trajectory groups were identified for dysmenorrhoea: normative (42%), late onset (11%), recovering (33%) and chronic (14%), with the chronic group showing high probabilities of reporting dysmenorrhoea over time. Compared with never-smokers, a significantly higher odds of being in the chronic group was detected for smokers, with ORs being 1.33 (95% CI 1.05 to 1.68) for ex-smokers and 1.41 (95% CI 1.17 to 1.70) for current smokers, after adjusting for sociodemographic, lifestyle and reproductive factors. An inverse relationship was identified for earlier age of smoking initiation, with the respective ORs of 1.59 (95% CI 1.18 to 2.15), 1.50 (95% CI 1.18 to 1.90) and 1.26 (95% CI 1.03 to 1.55) for initiation of smoking ≤13, 14-15 or ≥16 years. No consistent relationship was evident between smoking behaviour and the odds of being in the other trajectory groups. Conclusions Smoking and early initiation of smoking are associated with increased risk of chronic dysmenorrhoea. The immediate adverse health effects of smoking provide further support for smoking prevention programme to target young women, especially teenagers. [ABSTRACT FROM AUTHOR]