A multicentre, double-blind, randomized trial of prophylactic esketamine to reduce postpartum depression in first-time mothers was published in the European Journal of Anaesthesiology in early 2026, and it drew enough immediate correspondence to suggest the result is being argued over rather than accepted. That is the right reaction, and not because the trial is bad. It is because this study is the latest entry in one of the most-replicated questions in the ketamine literature, and the body of work keeps arriving at the same unsatisfying place: a genuine short-term signal, measured on a screening instrument, in a clinical setting that confounds it, that tends to disappear before the point at which it would matter.
What the trial found
In the published trial, postnatal first-time mothers were randomized to receive esketamine, a single intravenous dose of 0.25 milligrams per kilogram followed by 80 milligrams added to 24-hour patient-controlled intravenous analgesia, or an equal volume of saline. The authors concluded that perioperative adjunctive esketamine is relatively safe and can prevent postpartum depression in first-time mothers without a predisposition to prenatal depression in the short term. Every qualifier in that sentence is load-bearing: relatively safe, adjunctive, without predisposition, in the short term. The trial is registered and multicentre, which makes it among the stronger entries in this literature, and its own conclusion is still hedged on duration and population.
The pattern across a decade of trials
This is not a new question. A substantial run of randomized trials, most conducted in Chinese anesthesiology departments around labor analgesia and cesarean delivery, has tested ketamine or esketamine given around childbirth to prevent postpartum depression. They have used a range of doses, from 0.2 milligrams per kilogram to 1.5 milligrams per kilogram and various infusion-plus-analgesia regimens, and they converge on a recognizable shape. Esketamine reduces the rate of screening-positive postpartum depression in the early window, at four days, at one or two weeks, and then the separation from placebo often narrows or vanishes by six weeks. One representative trial found a benefit at four days that was gone by 42 days. A 2024 randomized trial in a major journal found that esketamine decreased early screening positivity but described the effect as transient. The meta-analyses that pool these studies note exactly this heterogeneity and time-dependence.
The volume of rapid correspondence around the new trial fits the pattern. When a result is both clinically appealing and methodologically fragile, it generates immediate published debate rather than quiet acceptance.
Why the result will not settle
Three structural features keep this literature from converting into a clinical claim.
The first is the outcome. These trials almost uniformly measure postpartum depression as a positive screen on the Edinburgh Postnatal Depression Scale, a screening threshold, not a diagnosis. Reducing the share of women who score above a screening cutoff in the early postpartum weeks is not the same as preventing postpartum depression as a clinical disorder, and the two are routinely conflated in the way these results are described.
The second is timing. The benefit clusters in the acute peripartum window and tends to fade by six weeks. Prevention that does not persist past the period when the drug and the delivery are still acutely present is difficult to distinguish from a transient mood effect, and postpartum depression is a condition defined over months, not days.
The third is the setting. Esketamine in these trials is delivered as part of labor analgesia or post-cesarean pain control. That entangles any antidepressant signal with pain relief, sedation, and the analgesic experience itself, which makes it hard to attribute an early mood benefit specifically to an antidepressant mechanism rather than to better-controlled pain and its downstream effects on mood and sleep.
Layered on top is the class context the desk has covered separately: the evidence that ketamine’s antidepressant action engages the opioid system, and the abuse-liability questions that follow the class, which are not trivial considerations when the proposed use is routine administration to healthy postpartum women.
The read
The honest summary is that prophylactic esketamine for postpartum depression is a promising signal that has repeatedly failed to become a definitive answer, and the failure is methodological rather than biological. The signal is real enough to keep generating trials. It is fragile enough, screening-based, short-lived, and confounded by the analgesia setting, that each new trial including this multicentre one reproduces the ambiguity rather than resolving it. The study that would settle the question has not yet been run: one that uses a diagnostic endpoint rather than a screen, follows women out past the acute window to the months over which postpartum depression actually presents, and separates the drug from the analgesia context. Until then, the appropriate characterization is not that esketamine prevents postpartum depression. It is that esketamine produces a short-term improvement on a depression screen in the days after delivery, which is a different and smaller claim.