Supplementary Material for: Smoking Trajectories during the Perinatal Period and Their Risk Factors: The Nationally Representative French ELFE (Etude Longitudinale Française Depuis l'Enfance) Birth Cohort Study

<strong><em>Background:</em></strong> In France, rates of perinatal smoking are among the highest worldwide; however, perinatal smoking trajectories and associated factors have still not been adequately researched. <b><i>Methods:</i></b> Among women participating in the French nationally representative etude longitudinale française depuis l'enfance birth cohort (<i>n</i> = 15,540), perinatal smoking trajectories were estimated using group-based modelling. Associated characteristics were studied using multinomial logistic regression. <b><i>Results:</i></b> Four trajectories were identified: non-smokers (59%), quitters (20%), persistent moderate (12%) and persistent heavy (9%) smokers. Older age, being native French, low socioeconomic position, persistent psychological difficulties and alcohol use in pregnancy, lack of social support, partner's smoking, mistimed pregnancy, and child formula feeding at birth were associated with persistent heavy smoking. Most of these factors were also associated, but to a lesser extent, with persistent moderate smoking, except for age and migrant status, which had opposite effects. Women who successfully lost weight prior to pregnancy had higher levels of quitting smoking. <b><i>Conclusion:</i></b> Women's long-term smoking trajectories vary in terms of initial tobacco consumption level but also in relation to socio-demographic, psychological, behavioral and partner characteristics. Health professionals in contact with pregnant smokers should address perceived risks and benefits of smoking, including partner's smoking and weight-gain concerns.