A good rule of thumb for horror cinema is that your movie can get away with being obvious, or it is allowed to be slow to unfold. But it can’t be both and work.

That’s the curse of “The Womb,” an occasionally tense but generally tedious horrors-of-giving-birth tale from Indonesia.

“Obvious” comes from its opening tease, a wizened shaman (Pritt Timothy) is being interviewed about a particularly unlucky day — by tradition — to give birth. He describes the remedy in vague terms, a “ritual” designed to “cut off…the misfortunes the baby comes with” (in Indonesian, with English subtitles).

That’s what the movie is about, a pregnancy facing a dangerous “Wekasan Wednesday” birth, and just what that “cut off” ritual involves.

But before anything like that can enter the picture, we need over a half hour of the story of unhappy Wulan (Naysila Mirdad), pregnant with a fair weather beau who tells her to “get rid of it.”

She lives in a tenement, and is late on the rent because sonograms aren’t covered by national health insurance. The landlord, overly fond of the sex worker living across the alley from her, doesn’t want to hear about it. Asking her boss at the big box home improvement store for an advance just earns her an unwelcome advance of a sexual nature.

So that’s three “problem” men in her life, not even taking into account her flashbacks to her unhappy childhood, where Dad and Mom fought constantly.

After taking suggestions from a friend and co-worker, consulting a pushy male operator on an unwanted pregnancy hotline, she stumbles across an older couple. Eva and Agus (Lydia Kandau, Rukman Rosadi) are desperate to adopt.

Next thing we know, she’s on her way to their big, remote country house, offered all sorts of health tips, “special” food and body oils by Eva and a sympathetic ear by Agus. It’s all good until the vivid nightmares start, triggering her growing suspicions about the place and these two, the midwife they consult and the shaman (Timothy again) they bring in. It’s enough to completely freak her out in her heightened, hormonal state.

And Wulan isn’t seeing all the stuff that director Fajar Nugros is showing us — the rat trapped in a cage in the garden shed metaphorically cut into the scene where Eva shows Wulan her room, what happens to rats when Agus is around.

“The Womb” takes its sweet time to get going, and drags out the assorted incidents that raise Wulan’s suspicions to the point where, whatever alarmed look Mirdad occasionally shows us, there’s no momentum for building a sense of rising paranoia.

Nothing really gets going until the third act, which is as good a time as any for the viewer to remember the “obvious” tease in the opening.

Remember, this is a Muslim country, and considering that, the movie’s very subject matter and treatment of sex is pretty racy and risky.

It’s a good looking film, with simple but effective effects and jolts of violence here and there. But it’s a bit obvious and entirely too slow in getting around to reminding us of that.

Rating: TV-MA, violence, sexual situations, smoking, profanity

Cast: Naysila Mirdad, Lydia Kandau, Rukman Rosadi, Dimas Anggara and Pritt Timothy

Credits: Directed by Fajar Nugros, scripted by Deo Mahameru. A Netflix release.

Running time: 1:56