What’s with all the maternity angst lately? First came Nightbitch, then If I Had Legs I’d Kick You, and now — in keeping with the rule that three makes it a trend — please welcome Mother’s Baby. Led by a fiercely compelling performance from Marie Leuenberger, Johanna Moder’s psychological thriller ticks along with exceptional confidence while it maintains ambiguity as to whether post-partum depression is feeding Julia’s paranoia or there really is something unsettling about her infant son, making her suspect a switcheroo at the private fertility clinic where she gave birth. It’s when the script starts providing answers that things get shaky.

Part of the issue is that the movie often seems to be itching to make a decisive turn into horror but keeps holding back. Moder and co-writer Arne Kohlweyer commit to that shift so late in the action that it all becomes a bit, well, silly. The bizarro outcome might also have packed greater shock value if it hadn’t been so plainly telegraphed at various points. That said, Mother’s Baby is juicy, disturbing and slashed with dark humor. It had me gripped for the duration, even at its loopiest.

Alongside Leuenberger’s tightly wound turn as accomplished classical orchestra conductor Julia — think Lydia Tár with a baby bump — the movie makes wonderful use of Claes Bang as Dr. Vilfort, head of the swanky but secretive Lumen Vitae clinic.

When the medic greets Julia and her husband Georg (Hans Löw), he’s all smooth reassurances, explaining that the facility uses all the latest research and has the highest success rate. He’s also convinced that just one treatment will make Julia pregnant, even though the couple has clearly tried many other options before shelling out the big bucks for Lumen Vitae.

With subtle intonations and the tiniest flickers of his facial expressions, Bang lets us know that Dr. Vilfort isn’t quite the nurturing miracle-worker he appears to be with his soft-spoken manner and crisp white lab coat. Creepy pets in movies are generally a red flag, and the doc has an office aquarium with an axolotl, a cannibalistic Mexican salamander with the ability to regenerate lost limbs. In terms of cuteness, it’s the hairless cat of the amphibian world, and if you’re thinking stem cells, you could be getting warm.

Just as predicted, Julia gets pregnant on the first try and all goes smoothly through the gestation period. Not so much when she goes into labor. In one of the most intense childbirth scenes in recent memory — squeamish mothers should approach with caution — Julia becomes increasingly panicked as the nurses keep multiplying, hurriedly implementing changes to the procedure. Robert Oberrainer’s camera slowly circles the delivery table throughout, adding to the sense that something is going very wrong.

When the baby boy does finally appear, he doesn’t make a sound and is whisked out of the room with the utmost urgency by Dr. Vilfort and midwife Gerlinde (Julia Franz Richter), before Julia even gets to see or hold him. The badly shaken new parents are told nothing for what seems like hours, until Vilfort appears to tell them the umbilical cord was wrapped around the baby’s neck, and due to an oxygen deficiency, the infant was taken to the general hospital’s neonatal ward. He assures them everything will be OK.

But when Vilfort returns the following day with their child, Julia remains distressed, eyeing the baby suspiciously as her agitation escalates into a full-blown anxiety attack. She has trouble breast-feeding at first, which prompts Gerlinde to advise switching to formula, going against the usual breast-is-best counsel of midwives. The fact that Julia keeps referring to the baby as “it” seems a good indication that maternal bonding won’t happen overnight.

When Julia and Georg get their son home, Moder begins to have some insidious fun with the scenario. Julia is not ready to commit to a name, so they give their son the “working title” Adrian, which horror connoisseurs will recall is the name given to the Mia Farrow character’s offspring in a certain Polanski film.

This Adrian might not be Antichrist material, but he doesn’t seem normal either, sleeping through maximum-volume noise, staring blankly ahead with eyes that seem to register nothing, and almost never crying, even when Julia gets caught up in her preparation for a Schubert concert and forgets to feed him for a whole day.

Leuenberger — who looks at times uncannily like Kathryn Hahn — is superb in these fraught scenes, leaning into unhinged behavior without ever making us question Julia’s rationality. There’s something shockingly funny about a mother giving a sudden full-fist squeeze to a squeaky toy right next to a baby’s ear just to get a reaction.

When she starts sawing vigorously away on a violin or pumping the stereo volume to thunderous levels on Sturm und Drang classical pieces, Georg begins to doubt her stability. “You wanted a child,” he shouts at her. “Yes, but not this one,” she replies. The script also touches on the identity loss that can accompany motherhood by having Julia fly into a rage after changes are made to the orchestra season program without consulting her.

Julia’s apprehension, which Leuenberger steadily builds to a cymbal-clash crescendo, isn’t helped by unsolicited visits from Gerlinde, who seems much more attached to Adrian than his mother. When the midwife cautions Julia that it’s unsafe to leave the baby unattended on a changing table, you can bet there’s going to an alarming fall. Gerlinde brings a gift from the doctor of a fishtank with an axolotl, which irks Julia but clearly seems adorable enough to Georg to make him pick up a companion for it. Bad idea.

As friction between Julia and Georg reaches a peak, he leaves with the baby to stay with his mother so that his wife can rest and get back to normal. But Julia’s fight to uncover the truth just becomes more and more desperate once she starts hearing vague reports of other mothers’ negative experiences at Lumen Vitae. Not to mention being told at the neonatal ward that there’s no record of her child’s birth.

In one of the most chilling scenes, Julia is taken to see Dr. Vilfort after being stopped from entering the clinic’s medical labs. He keeps a calm smile on his face and a measured tone of voice as he talks her through the potential custody issues and the ruin of her career that would likely result from an insanity diagnosis.

To Moder and Kohlweyer’s credit, there are valid points being made here about the frequent dismissal of women’s fears as mental health problems. But the progression from psychodrama to grotesque motherhood nightmare is too abrupt to be entirely convincing, even if it delivers a generous serve of lurid pleasures. Whether Julia’s freakish discoveries are real or in her mind, the movie could have benefited from being let off the leash earlier.

Still, even if it sits somewhat awkwardly between serious drama and horror, there’s plenty to enjoy here, from the terrific performances to the fiery use of music to Oberrainer’s razor-sharp widescreen images, which turn murkier and more overtly sinister in the purple-tinged final act.