Abstract: ObjectiveTo investigate the knowledge about passive smoking and its influence factors among early pregnancy women in Shanghai and to analyze the relationship between the knowledge and behavior of passive smoking,and to provide evidences for implementation of effective intervention on passive smoking in the population.MethodsA questionnaire-based survey was conducted in 3 729 eligible pregnant women from May 2011through May 2012.The relationship between knowledge and behavior of passive smoking was analyzed using Chi-square test and the influencing factors of passive smoking knowledge were analyzed using logistic regression.ResultsTotally 3 274 valid questionnaires were collected.The passive smoking rate in the participants was 44.7%.The awareness rate of diseases associated with passive smoking was 67.5%.Of the participants,94.5% knew that smoking or passive smoking might cause lung cancer,but the awareness rates of other diseases associated with passive smoking were low (77.9% for emphysema,75.5% for aging,54.4% for heart disease,54.2% for stroke,and 48.7% for asynodia,respectively).The awareness rate of adverse effects of passive smoking on pregnant women was 64.2%.No significant association was found between passive smoking knowledge and the passive smoking behavior.Among the participants,employment was a main influencing factor of knowledge about passive smoking and the employed pregnant women had higher awareness rates for associations of smoking or passive smoking with diseases and adverse effect of passive smoking on pregnant women than those without employment,with the odds ratio of 1.399 and 1.276.ConclusionHealth education on passive smoking needs to be improved and the unemployed women is a key population for intervention on passive smoking among pregnant women in Shanghai.