Objective: To describe the prevalence of depression during the first and second trimester of pregnancy, and to explore the correlation between them.
Methods: 1051 pregnant women were investigated by the EPDS in the first and second trimester of pregnancy.
Results: The prevalence of depression were 33.11% and 19.86% in the first and second trimester of pregnancy respectively, and 64.11% depressive women of the second trimester are also depressive in the first trimester. There was significant difference between the prevalence of the two trimesters（ 2=47.190，P<0.01）.
Score of every item and total score in the first trimester were all higher than that in the second trimester significantly. Score of every item in the first trimester showed positive correlation with the total score in the second trimester, especially these three items:
Conclusions：Depression is very common in the first trimester of pregnancy, and it has positive correlation with that in the second trimester. Some women with depressed mood in the early trimester will last for a long time, even to postpartum period, so we should find the women with high risk and take some interventions as early as possible to reduce the rate of prenatal depression.
Key Words: Gestation；Depression；Correlation