Introduction: Anxiety and depression during pregnancy could affect the neonatal outcomes and preterm Delivery. The Aim of this study is to analyze the relationship between maternal anxiety and depression in third trimester pregnancy on growth index of neonates and preterm delivery in laboring women who referred to Hamadan's medical and health district centers in 2011-2012.

Methods: In a descriptive cross-sectional study 250 pregnant women in third trimesters using several stage cluster sampling were selected, and data were achieved from three questionnaires, Demographic data, Edinburgh’s Depression and Van den Bergh’s anxiety during pregnancy. Huizink and et al state that Van den Bergh’s 10 questionnaires of anxiety in third trimester pregnancy has a good content. They obtained the reliability of the subscales of this questionnaire about the fear of preterm delivery equal to /083 and fear of delivering a baby with mental and physical disabilities, equivalent to /087 and Concerns about the appearance equivalent to 0/83.  Related to Edinburgh’s questionnaires, using the method of determination of correlation coefficient of Edinburgh’s test at the same time and Beck‘s the anxiety test equal 0/78 is attained. The reliability of this test from Cronbach's alpha and split-half method was estimated equal to /088. To analyze, we used descriptive statistics, spearman correlation coefficient, Kruskal-wallis and Mann-Whitney U.

Results: Mean score of maternal anxiety and depression in third trimester pregnancy of cases were (30/7±7/9) and (12/3±4/1) respectively. Data analysis showed no significant relationship between anxiety and depression of third trimester pregnancy and the neonates on growth index (p>0/05), but a positive relationship between maternal anxiety and depression on preterm labor was found (p<0/05).

Conclusion: According to the study findings and positive relationship between maternal anxiety and depression on preterm labor, planning preventive and supportive programs by the specialists who work with pregnant women's mental health are necessary