Background:Postpartum depression has been the focus of much research in the past 15 years, but little is known about factors associated with depression of longer duration or later onset. The purpose of this longitudinal study was to analyze the relationship between stressful life conditions and postnatal depression in a group of women of low socioeconomic status from the third week to the sixth month postpartum.Methods:Nulliparas who met criteria for low socioeconomic status were recruited from the prenatal care clinics of four Montreal hospitals. Questionnaires were verbally administered in the home at 30 weeks' gestation, at 3 and 9 weeks postpartum, and at 6 months postpartum. Blockwise multiple linear regression analyses were performed by entering predictor variables that included sociodemographic characteristics, chronic stressors, life events, and social support network.Results:Sixty-eight women participated in the study. At 6 months postpartum, 38.2 percent of the mothers had a Beck Depression Inventory score of 10 or more. After accounting for previous depression, analyses indicated that chronic stressors (maternal health problems, infant difficulty, lack of money for basic needs, frequent conflicts with network members) and poor social support (informational and emotional) were associated with postnatal depressive symptoms.Conclusions:Health practitioners should recognize that high depressive symptomatology frequently occurs among low socioeconomic status first-time mothers at six months postpartum. Chronic stressors and inadequate social support are the most important factors associated with this problem.