Maternal stress has been identified as an epidemic that has a detrimental effect on work productivity and personal and professional growth. Objectives: To determine maternal stress and its associated factors among working nurses in public sector tertiary care teaching hospitals in Karachi, Sindh. Methods: The analytical cross-sectional study was accomplished at Dr. Ruth K.M Pfau Civil Hospital Karachi and Dow University Hospital Karachi. A total of 131 nurses were approached by a convenient non-probability sampling method. The Parental Stress Scale was used for data collection. Data were entered and analyzed by using SPSS version 24.0. Chi-square test was applied out to find an association between maternal stress and associated factors. Results: Nurses reported 72 (55%) mild parental stress, 58 (44.3%) parental moderate stress, and 1 (1%) severe parental stress. Nurses belonging to the younger age group, widowed or divorced, had mild parental stress, while nurses who lived with their husbands had lesser moderate stress. Female participants with one child of either gender, whose more family members were earning, had less tendency to have mild parental stress. A statistically significant association was found between working nurses' parental stress level and age group (p-value=0.005). Conclusions: It was concluded that nurses reported mild, moderate, and severe maternal stress. Hence, it is increasingly imperative to create facilities like daycare centers and offer them the flexibility to perform their job effectively