Nowadays, there is increasing non-return to work in pregnant workers. Therefore, the objective of this study was to explore the association between general characteristics, occupational, maternal and infant factors and women returning to work after pregnancy for further improve occupational health service in this population. The retrospective cohort study was conducted in July 2012 at Nopparat Rajthanee Hospital, Bangkok. The data were interviewing workers at Well baby clinic, Nopparat Rajthanee Hospital and Satellite Health Centers. The total population was women who delivered at this hospital in January 2012 and worked before delivery. 584 pregnant workers were included in this study, yielding the cover rate 82.60%. The analysis was performed by percentage and regression. The result found that the proportion between returned to work and non-returned to work 6 months after delivery was 4:1. There are three general characteristic factors with statistical significance associated with returning to work, which include age (p-value 0.002), number of pregnancy (p-value < 0.001), and source of income (p-value <0.001). In addition, there are eight occupational factors with statistical significance associated with returning to work consisting of occupation (p-value 0.03), employment status (p-value 0.03), working sectors (p-value <0.001), fulltime or part-time (p-value <0.001), work posture such as standing (p-value <0.001), sitting (p-value <0.001), walking (p-value 0.048), and poor ergonomic posture (p-value 0.02). Furthermore, there is one maternal factors with statistical significance associated with returning to work, which was postpartum hematoma (p-value 0.003). However, there are no infant factors with statistical significance associated with returning to work. In conclusion, this study found factors related to returning to work. The occupational health provider should include these factors for holistic care in this working population.