Postpartum depression, a common complication in childbearing women, is of great public health concern. Previous screening tools have focused on depressed mood, with less attention paid to postpartum anxiety and suicidal ideation. This study developed and validated a tool to measure postpartum depression among mothers of preterm babies. From the clinical interviews and a pilot survey (n=121) the Mothers of Preterm Babies Postpartum Depression Scale was developed. The Mothers of Preterm Babies Postpartum Depression Scale and the Edinburgh Postnatal Depression Scale questionnaires were completed by 152 mothers who delivered preterm babies at Massey Street Children’s Hospital, Lagos. Data were analyzed with use of confirmatory factor analysis, principal component analysis, and Cronbach’s alpha at the P≤0.05 level of significance. The new scale demonstrated a reliability (α) of 0.91. Construct validity with exploratory factor analysis (Kaiser-Meyer-Olkin measure 0.70) yielded three dimensions of cognitive and emotional difficulty (α=0.92), hopelessness and suicidal ideation (α=0.93), and physiological distress (α=0.71). Confirmatory factor analysis demonstrated a good fit: 18 degrees of freedom; goodness of fit index 0.97; adjusted goodness of fit index 0.93; and root mean square error of approximation 0.04. Convergent validity was established with the Edinburgh Postnatal Depression Scale (r=0.66, P=0.00). The new screening tool was demonstrated to have meritorious validity, faster and easier to administer to the obstetric population.