The aim of this study was to analyse the influence of personality factors and antenatal depressive symptomatology in postnatal depression. A prospective ex post facto design was carried out. The sample consisted of 116 women, recruited in their first trimester of pregnancy and followed up until four months postpartum. The measurement instruments used were the Edinburg Postnatal Depression Scale (EPDS) to assess postpartum depression, the NEO-Five Factor Inventory (NEO-FFI) to analyse personality traits and the depression subscale of the Symptoms Check List 90 (SCL-90-R) to assess depressive symptomatology in the first half of pregnancy. Socio-demographic variables (age, parity, educational level, employment status, and planned pregnancy) and clinical variables (neonatal Apgar score and mode of delivery) were also taken into account. A positive correlation was found between postpartum depression and depressive symptomatology in the first trimester; however after the regression analysis neuroticism was the only factor that predicted postpartum depressive symptoms, explaining 24.8% of the variance. Neuroticism significantly influences psychological health during life events such as motherhood. Due to its stable condition, personality could be assessed from the beginning of pregnancy, contributing to the care of pregnant women with high scores in neuroticism, to prevent, detect and treat early postnatal depression.