Pregnant heroines can be fascinating, funny, complex characters, though few have been as memorable as Mia Farrow in Rosemary’s Baby, the mother of all pregnancy movies. Roman Polanski’s 1968 horror was notable for showing events from the pregnant woman’s point of view as Farrow began to suspect her neighbours of sinister designs on her unborn. A nativity story it was not.

The fearful expectant mother is a familiar horror movie trope – and many of them have good reason for concern. From Charlize Theron in The Astronaut’s Wife to the women in Village of the Damned, the prospect of an alien on board is terrifying. More recently, Twilight: Breaking Dawn played on the fears of teen mothers – and took a radically pro-life stance – as Kristen Stewart opted to die in childbirth rather than abort the vampire baby that was consuming her from within.

It’s a rich subject for an exploration of life, death, terror and turmoil – which is why British writer and actor Alice Lowe, star of 2012’s Sightseers, is such a fan of the genre. Lowe has chosen a pregnant protagonist for her directorial debut, Prevenge, which she calls “a darkly comic drama about a murderous mother-to-be”. She also starred in the project while seven months pregnant and says the idea was initially a practical one. “I was asked if I wanted to develop a low-budget film with a quick turnaround. At first I thought I’d have to say no, but then it occurred to me that I could do it if it centred around a pregnant character.”

British writer David Farr decided to feature not one but two expectant mothers in his big-screen directorial debut, the psychological thriller The Ones Below. Clémence Poesy plays Kate, a Londoner intrigued by her equally pregnant new neighbour, Teresa (Laura Birn). Farr was keen to explore the separate anxieties of two women going through the same thing. “Every mother is different. Kate has a particular past that infects her confidence as a mother. Teresa is a zealous and uber-loving mother-to-be. Pregnancy is their condition – the character is something else.”

It’s refreshing to note that both The Ones Below and Prevenge focus on complex women whose pregnancies don’t define them. All too often expectant movie mothers inhabit the sidelines, either as a plot device, adding complications for the hero, or providing comic relief. Even when putting a pregnant woman in the spotlight, 80s and 90s Hollywood took a comical approach, from She’s Having a Baby and Look Who’s Talking to Nine Months. And then of course there was Junior, in which Arnold Schwarzenegger was expecting.

“Apparently it’s only a fascinating dramatic crisis when it’s happening to a man,” says Lowe. “I think there is still the idea of ‘confinement’ – that pregnant women should not be seen or heard. And so we don’t see them on screen unless they are the butt of some kind of comedy: crazy pregnant lady, screaming giving birth, demanding things, eating like a pig, waters breaking everywhere.”

In 2007, the pregnancy-comedy genre was reborn with Juno, the whipsmart indie introducing Ellen Page as a teenager confronting an unplanned pregnancy. Judd Apatow’s witty Knocked Up appeared the same year. Loosely inspired by a self-help book, 2012’s What To Expect When You’re Expecting, a broad, fitfully patronising comedy did at least acknowledge that both pregnancy and motherhood come in many forms. Jennifer Lopez’s Holly opts to adopt while Cameron Diaz’s fitness trainer is shocked to fall pregnant by her TV show dance partner.

Prevenge will be different, says Lowe. “You expect a mother to be nurturing, kind, sweet, placid, almost dopey, weak, a victim, needing help, someone to be rescued or protected. Almost like an object, entirely passive. My character is anathema to that. I don’t know if she would exist, but it’s someone who has gone beyond the bounds of normal human behaviour, and has become a vessel for anger. She’s stepped outside of society.”

So do Farr and Lowe’s films represent a shift towards a more progressive attitude? It’s possible. The conversation about women in film – on both sides of the camera – continues. If their presence grows, writers and directors will be less likely to marginalise pregnant characters. A recent study from San Diego State University claims that female leading characters in the top 100 US box office films went up by 10% last year (still only 22%). In the past year or so, films featuring complex pregnant characters have included the post-apocalyptic Oscar-winner Mad Max: Fury Road, in which a harem of young women are rescued and empowered by feminist heroine Furiosa. A heavily pregnant Angharad doesn’t just square up against the men but climbs across moving vehicles and wields her belly as a potential bargaining tool.

Meanwhile, smart stalker thriller The Gift was shown from the point of view of Rebecca Hall’s would-be mother Robyn, an intelligent, intuitive character whose story arc hinged around much more than her fertility as she probed the mysterious past of her husband and his creepy schoolmate. Sundance hits Obvious Child and Grandma had pregnant leads and broke a bigger taboo: both women were seeking abortions.

But cliches still abound. Everest, In The Heart of the Sea and The Night Before all featured the pregnant wife back home (even though the character in the last playfully bucked stereotypes by gifting her husband recreational drugs). Miss You Already saw a pregnant Drew Barrymore comforting her cancer stricken friend, but it was the latter who was allowed to behave badly. Barrymore’s character was the typical nurturing, maternal earth mother type.

More pregnancy comedy is due in six months when Renee Zellweger returns in Bridget Jones’s Baby. Bridget finds herself pregnant by an unknown father, with Colin Firth and Patrick Dempsey in the frame. In narrative terms, it seems plausible that this could be a next step for Helen Fielding’s comical character and her complicated love life – and marketing wise, it’s bound to strike a chord with her fans, many of them having gone on to start a family.

Culturally speaking, rendering a post-feminist icon of the 90s pregnant seems a little conventional, but word on the script – which is not based on Fielding’s third book – suggests that Bridget will continue to carve her own quirky path through life. Three different endings have been shot, so not even Zellweger knows how this story will conclude, but there’s every hope the film will present a fully rounded heroine whose baby bump is just one part of the story.

Perhaps the most progressive pregnant character, though, is one who barely mentions the condition at all. “I think Frances McDormand in Fargo has to be the ultimate pregnant character,” says Lowe. “The pregnancy is rarely alluded to. I’d like to see more characters who just happen to be pregnant without it being their sole purpose.”

• The Ones Below is out on 11 March, and VOD in the US from 27 May. Prevenge will premiere later in 2016