This summer, a Massachusetts courtroom has confronted one of medicine’s most misunderstood conditions. Lindsay Clancy is on trial for infanticide in her Duxbury home in January 2023. Her defense argues she was in the grip of postpartum psychosis, a rare and catastrophic psychiatric emergency, at the time of the killings; prosecutors counter that her actions were deliberate. Whatever the jury decides, the case has exposed a gap in public and clinical understanding of postpartum psychosis itself — what it actually is, how different it is from the conditions most commonly associated with pregnancy, and why that confusion carries real consequences for mothers and children.

To better understand the diagnosis and management of mental health conditions associated with pregnancy, I spoke with Dr. Patricia De Marco Centeno, a board-certified consultation-liaison and reproductive psychiatrist. Here, she describes the terminology and in a subsequent article she shares the challenges of treating these conditions.

Understanding the Terminology

The umbrella term now used is perinatal mood and anxiety disorders, or PMADs — a category that captures depression, anxiety, and obsessive-compulsive disorder that can emerge anywhere from early pregnancy through the first year postpartum. Centeno clarified that in the field of reproductive psychiatry, clinicians have largely moved away from "postpartum depression" as a term in favor of perinatal depression, "since depression frequently begins during pregnancy, not just after, or 'post,' delivery."

Most of what falls under PMADs is common and comparatively benign: postpartum blues, a well-recognized clinical phenomenon affecting up to 80% of new mothers, presenting as roughly two weeks of tearfulness or irritability that doesn’t significantly obstruct bonding or daily function. Two other conditions — perinatal depression and perinatal obsessive-compulsive disorder — also sit squarely inside the PMAD umbrella.

What Is Perinatal Depression?

Perinatal depression looks like profound low mood, tearfulness, or irritability, along with changes in sleep and appetite that aren’t fully explained by the demands of caring for a newborn. Centeno especially looks for a sense of hopelessness — where patients express a feeling that there’s no way out, or no improvement coming — as the marker that symptoms have crossed from ordinary adjustment into something that needs treatment. "The clearest diagnostic signal isn’t symptoms lasting beyond the two-week cutoff of 'postpartum blues,' but functional impairment: a mother who can no longer carry out her daily activities, or care for herself or her baby, the way she could before," Centeno says. Perinatal depression, she adds, affects up to one in five women, rarely poses any danger to the infant, and responds well to standard treatment.

What Is Perinatal Obsessive-Compulsive Disorder?

Perinatal obsessive-compulsive traits are common in the perinatal period and present as contamination fears, excessive cleaning or checking, and intrusive thoughts centered on the fear of accidentally harming the baby. Centeno is careful with the term, however: "it is very rare that somebody meets full criteria for obsessive compulsive disorder" — most mothers are experiencing a flare of OCD-like traits, not the diagnosable disorder itself, though the perinatal period is unique in how strongly it can trigger themThe quintessential example, according to Centeno: "I'm gonna drop the baby." These thoughts are egodystonic — incongruent with the mother's own values and self-image — which is exactly why they're so disturbing to her, not because she has any intent to act on them. This diagnosis of perinatal OCD comes with no signs of psychosis: no delusions, no hallucinations, no disorganized behavior.

Mothers with perinatal depression and OCD know something is wrong, Centeno says — they’re often crying, afraid, or hesitant to speak up for fear of how the thoughts will be interpreted, but they recognize the thought as a symptom, not a plan.

The most interesting point Centeno raised is the term anosognosia: "mothers with psychosis do not have insight, and this is not intentional. It’s simply a neurological condition in which you do not know that you’re ill." That distinction — insight versus its absence — is where perinatal OCD and depression part ways from postpartum psychosis.

What Is Postpartum Psychosis?

Postpartum psychosis (PPP) is rare, occurring in one to two out of every 1,000 births. What’s most surprising is that it isn’t a standalone diagnosis that starts with pregnancy and resolves once the postpartum period ends — the way gestational diabetes often does, where a mother who was never diabetic before becomes diabetic during pregnancy, then isn’t afterward. Postpartum psychosis works differently: in up to 70% of cases, postpartum psychosis is actually the first acute presentation of bipolar I disorder — a chronic illness that pregnancy unmasks rather than causes. (In the rarer cases where a mother already has a diagnosis like schizophrenia, pregnancy can simply exacerbate that existing illness.) Classically, bipolar I itself is defined by manic episodes — extended stretches, usually lasting a week or more, marked by elevated or irritable mood and a surge in goal-directed activity, sometimes with psychotic features like delusions or hallucinations. “Sleep pattern is one of the clearest tells,” Centeno says. A manic episode brings a decreased need for sleep, not insomnia — the person might sleep two hours a night and simply not feel tired, often channeling that extra energy into a surge of goal-directed activity. Insomnia looks different: “the person can’t sleep, but feels exhausted by it,” she adds.

“What makes bipolar I so dangerous in pregnancy is how it moves,” says Centeno. A manic episode outside the perinatal period tends to last weeks or months until treated. Postpartum psychosis waxes and wanes within hours. Centeno says a mother can be calmly preparing breakfast one moment and, an hour later, be convinced her baby has been replaced by an impostor, or that her husband is an actor, with a fixed belief that something drastic must be done to save herself or her child. That belief can turn toward suicide or infanticide, both understood by the mother, under the influence of the delusion, as acts of protection rather than harm.

"The idea of altruistic infanticide or suicide ‘makes sense’ to the mother because they feel their children are genuinely and seriously threatened under the delusional system they’re in. In her mind, the children are in great danger." explains Centeno. Centeno is careful about the statistics here, since the condition is hard to measure, but notes that “the risk of suicide is higher than the risk of infanticide” — with estimates running up to roughly 5% and 4%, respectively.

Understanding the difference between OCD, depression and psychosis

The clearest way to separate these conditions is by looking at insight and intent. Centeno describes PPP thoughts as often "egosyntonic" — the delusion doesn't feel foreign or wrong from the inside; it feels like urgent, necessary truth. A mother with perinatal depression or OCD typically knows something is wrong and wants help; a mother in postpartum psychosis often does not believe anything is wrong at all, which is exactly why waiting for her to ask for help, rather than actively evaluating and treating her, can have catastrophic outcomes.

This disconnect in insight and intent is exactly why perinatal and postpartum mental health concerns need more attention and education — starting with why postpartum psychosis, in particular, keeps slipping past the doctors seeing these mothers first, and what happens when treatment itself goes wrong. In Part Two, Centeno and I dig into exactly that.