Background & Aim: Depression is the most prevalent mental disorder with the 4-20% prevalence during pregnancy. The evaluation of stress causing situations and social support and their relation with depression can be used as evidence for diagnosis of depression and cause to necessary background to preventive and effective work. The aim of this study was to assess the relation of depression during pregnancy with social support and negative life events.
 Material and Methods: This is a cross sectional study that was carried out on a group of 200 pregnant women in Aran- Bidgol. The data collection instruments were demographic are, Beck inventory, Social support and Negative life events questionnaires. The data were analyzed with descriptive and analytical tests.
 Results: The prevalence of depression was 41% Mild, moderate and severe levels were 27.5%, 11% and 2.5% respectively. There was a significant relation between depression and social support(r=-0.37, p < 0.001) and negative life events(r=0.42, p < 0.001).There was a significant difference in social support (p < 0.05) and negative life events (p < 0.05) between depressed and non depressed groups.
 Conclusion: With regard to the high prevalence of depression in this study in companion  to some other studies in Iran and significant relation between depression during pregnancy and social support and negative life events, necessity of patient finding during pregnancy is suggested. Increase of social support and decrease of negative life events may be effective to prevention of depression during pregnancy.