There is a dearth of data on the causes of postpartum depression, and the effects of prenatal sleep disorders on the development of postpartum depression among pregnant women have not been studied well. A study, published in Oncotarget, aimed to understand the association between prenatal sleep disorders and postpartum depression. Data from the National Health Insurance Research Database of Taiwan (between 2000 and 2010) was used to assess the effects of prenatal sleep disorder on the risk of postpartum depression using Cox regression analyses. It was noted that prenatal sleep disorder in pregnant women increased the risk of developing postpartum depression (5.359-fold increased risk compared with control cases). Irrespective of the postpartum week (≤ 6 weeks, 6-12 weeks, or > 12weeks), the risk of developing postpartum depression in pregnant women with prenatal sleep disorders was increased by 5.461-fold, 3.490-fold, and 3.416-fold, respectively, compared with pregnant women without sleep disorders. It was thus concluded that pregnant women with prenatal sleep disorders had increased risks of developing postpartum depression. Therefore, postpartum interventions should be introduced as early as possible to reduce the risk of postpartum depression among pregnant women with prenatal sleep disorder.