Background: The burden of postpartum depression is significant because it remains unrecognized and it not only affects the mother adversely but also has a negative consequence on the family life and the development of the infant. This research aims to aid the early diagnosis of postnatal depression using Edinburgh postnatal depression scale (EPDS) and the psychosocial and reproductive risk factors of postnatal depression among women delivering in a tertiary hospital in Kerala state, India.Methods: 500 women were subjected to a standard questionnaire for assessing psychosocial and reproductive characteristics. The diagnosis of postnatal depression was made using a pretested and validated Malayalam version of EPDS with a score cut off of 13 or more.Results: The proportion of postnatal depression six weeks after delivery at TD Medical College, Alappuzha was found to be 8.6%. Marital harmony (p value=0.002) was significantly associated with postnatal depression. Diabetes (p value=0.037), hypertensive disorders (p value=0.013), antepartum hemorrhage (p value=0.036), neurological disorders (p value <0.001), type of delivery (p value=0.042), postpartum complications (p value=0.003), mode of infant feeding (p value=0.001), infant illness (p value=0.001), symptoms of maternity blues (p value <0.0001), premenstrual syndromes (p value=0.008) and infertility treatment (p value=0.03) were significantly associated with postnatal depression.Conclusions: Early screening of the women and counselling of women and their family will reduce the maternal morbidity and adverse child outcomes