OBJECTIVE: To determine the current status of environmental tobacco smoke (ETS) exposure in new mothers living in urban Shanghai. STUDY DESIGN AND SETTING: A cross-sectional study was carried out in three communities of Shanghai from June 2005 to August 2006. A total of 950 new mothers with infants aged 5-8 months were recruited in community health centers by trained health workers. The prevalence of ETS exposure was determined for before, during, and after pregnancy. Chi-square test and logistical regression analysis were used in statistical analysis. RESULTS: The prevalence of ETS exposure was 55.9% (95% confidence interval [CI]: 52.2, 59.6) before pregnancy and decreased significantly to 41.9% (95% CI: 38.2, 45.6) during pregnancy. However, the amount and time of exposure to ETS changed little before, during, and after pregnancy for those exposed. Among husbands who ever smoked, 14.4% stopped smoking before pregnancy, 38.1% changed smoking behaviors during pregnancy, and after pregnancy 10.7% quit smoking, whereas three nonsmoking husbands began to smoke. CONCLUSION: Pregnancy is a very important time period to implement tobacco control projects targeting young male smokers.