Threatened preterm birth is the third most common cause of sick leave during pregnancy in Slovenia. There is no evidence that sick leave may reduce the risk of preterm birth. However, there are data that indicate that excessive workload may lead to preterm birth. Slovenian legislation allows pregnant women to be protected against such occupational stress. More and more pregnant women are exposed to various workload environments. The article presents an overview of the most important research on the impact of workload in the workplace in terms of the risk for preterm birth. We also report Slovenian data on frequency and most common causes of sick leave during pregnancy and trends in sick leave due to threatened preterm birth over time.