Forest plot showing risk of hallucination.

<div><p>Objective</p><p>Postpartum depression (PPD) is a major mental health issue affecting 10%–15% of women globally. This meta-analysis synthesized updated evidence on sub-anesthetic ketamine/esketamine’s efficacy in preventing PPD.</p><p>Methods</p><p>Randomized controlled trials (RCTs) comparing ketamine/esketamine to a placebo for PPD prevention were searched without language restriction. Primary outcomes were PPD risk at 1- and 4–6-week postpartum. Secondary outcomes included the difference in depression scores and risk of adverse events. Trial sequential analysis (TSA) was conducted to validate the reliability.</p><p>Results</p><p>A meta-analysis of 22 RCTs (n = 3,463) showed that ketamine/esketamine significantly decreased PPD risk at 1- (risk ratio [RR], 0.41; 95% confidence interval [CI], 0.3–0.57) and 4–6-week (RR, 0.47; 95%CI, 0.35–0.63) follow-ups. Consistently, participants receiving ketamine/esketamine had lower depression-related scores at 1- (standardized mean difference [SMD], −0.94; 95%CI, −1.26 to −0.62) and 4–6-week (SMD, −0.89; 95%CI, −1.25 to −0.53) follow-ups. Despite potential publication bias, TSA confirmed the evidence’s reliability. Subgroup analysis showed that ketamine/esketamine’s preventive effect on 1-week PPD was consistent, regardless of administration timing, type of agents, or total dosage (<0.5 vs. ≥0.5 mg/kg). For the 4–6-week period, PPD risk was favorably reduced only with postoperative administration or the use of esketamine, with the total dosage having no observed influence. Participants on ketamine/esketamine experienced more frequency of hallucinations (RR, 4.77; 95%CI, 1.39–16.44) and dizziness (RR, 1.36; 95%CI, 1.02–1.81).</p><p>Conclusion</p><p>Our findings advocate for the postoperative administration of low-dose ketamine/esketamine to avert PPD, which needed additional research for confirmation.</p></div>