Postpartum depression is a common psychological abnormality during the puerperium, which seriously affects maternal and neonatal health. Esketamine, the S-enantiomer of ketamine, is twice as potent as ketamine and can be safely used for cesarean section and labor analgesia. However, it is not clear whether esketamine used for epidural labor analgesia can significantly reduce the incidence of postpartum depression. This study intends to explore the incidence of maternal prenatal depression and to investigate the effect of esketamine for epidural labor analgesia on postpartum depression and maternal and neonatal outcomes in parturients with prenatal depression through a multi-center, large-scale and high-quality clinical trail, in order to provide a clinical basis and theoretical basis for the application of esketamine used for epidural labor analgesia in postpartum depression and further reduce the incidence of postpartum depression, promote maternal and infant health, and ensure maternal and infant safety .

The study include women who meet the inclusion criteria for antenatal EPDS score ≥10 for labour analgesia while signing informed consent. The women will be randomized into two groups, one for esketamine group and the other for the control group. Follow-up visits will be conducted at 1 day, 7 days and 42 days after delivery. The primary endpoint of the study was the incidence (MINI-6.0 for diagnosis of postnatal depression) and severity of maternal depression at day 42 postpartum. The secondary endpoints of the study are maternal EPDS scores at 7 and 42 days postpartum; pain scores and impact at 1, 7 and 42 days postpartum; breastfeeding at 1, 7 and 42 days postpartum; length of postpartum stay; maternal complications at 42 days postpartum and neonatal illnesses at 42 days postpartum.

Inclusion Criteria:

• Full-term pregnancy; Antenatal depressive state (EPDS score ≥10 and non-depressive diagnosis by a psychiatrist); Epidural labor analgesia； Signed informed consent.

Exclusion Criteria:

• Pre-existing history of definite psychiatric disorders (depression, schizophrenia, etc.) or communication disorders；Presence of severe preoperative pregnancy complications (e.g., severe preeclampsia, placental implantation, HELLP syndrome, placenta praevia, placenta abruptio)；ASA classification ≥ grade III；Contraindications to ketamine/S-ketamine (e.g., intractable, refractory hypertension, severe cardiovascular disease [cardiac function class ≥ III], hyperthyroidism); Refusal to participate in the study.