Prenatal depression is an important risk factor of postpartum depression. Low-dose ketamine has been used for depression treatment. As a stereoisomer of ketamine, s-ketamine has similar effects to ketamine in anti-depression. We speculate that, for pregnant women with prenatal depression, low-dose s-ketamine infusion after childbirth may reduce the incidence of postpartum depression.

Studies have shown that prenatal depression symptoms are important predictors of postpartum depression. Screening of pregnant women's mental condition before giving birth, early identification of pregnant women with symptoms of prenatal depression, and providing appropriate interventions may play an important role in reducing the incidence of postpartum depression. Ketamine is an NMDA-receptor antagonist. In recent years, many studies confirmed that ketamine has a significant antidepressant effect. As a stereoisomer of ketamine, s-ketamine has similar effects to ketamine in anti-depression. In clinical application, s-ketamine has stronger analgesic effect, better anesthetic effect and lower incidence of adverse psychological reactions. We speculate that, for pregnant women with prenatal depression, low-dose s-ketamine infusions after childbirth may reduce postpartum depression. Evidence is lacking in this regard.

Inclusion Criteria:

• Parturients with age ≥18 years;
• Presence of prenatal depression (EPDS score ≥10);

Exclusion Criteria:

1. A clear history of mental illness (depression, schizophrenia, etc.) or communication difficulties;
2. Severe pregnancy complications, such as severe preeclampsia, placental implantation, HELLP (syndrome hemolytic anemia, elevated liver function and low platelet count) syndrom, placenta previa, and placental abruption;
3. American Society of Anesthesiologists classification ≥III;
4. Presence of contraindications to ketamine/s-ketamine use, such as refractory hypertension, severe cardiovascular disease (New York Heart Association classification ≥III), and hyperthyroidism.