Objectives: To examine sociodemographic, physical, psychological and environmental factors that may be associated with vaginal bleeding (VB) in the first trimester. Methods: A questionnaire survey was conducted on 14,752 women by trained doctors, when pregnant women came for the first antenatal examination, including sociodemographic characteristics, prior adverse pregnancy outcomes, diseases history, life event stress, adverse environmental exposure and detailed information on VB. Results: VB occurred among 3,466 pregnant women, the prevalence of VB was 23.4% in the first trimester, 35.9% of whom did not see a doctor, 59.7% of whom went to clinic and only 4.4% of whom were hospitalized for VB. Multinomial logistic regression demonstrated that the following risk factors may be associated with VB with seeing a doctor: age >25 years, education greater than primary school, urban residence, prior spontaneous abortion, prior surgical abortion and previous stillbirth, having gynecological inflammation, chest X-ray examination and life events stress score >2 during the periconception period. Age >25 years, urban residence, prior surgical abortion, having gynecological inflammation and a life event stress score >2 during the periconception period may be related to VB without seeing a doctor. Conclusions: This epidemiologic study provided more information on predictors of VB: physical, psychological and adverse environmental exposure were all associated with VB in the first trimester.