Interview: Neve McIntosh finds her new role as a woman who has suffered miscarriages is emotional

"I don't want to sound poncy, but you do connect with things," says the 37-year-old star of Gormenghast, Low Winter Sun and medical drama Bodies, her voice cracking.

The cause of her tears is a little-known play by Sylvia Plath. Broadcast by the BBC's Third Programme a year before the poet's suicide in 1963 and revived only once since, Three Women is an evocation of pregnancy, childbirth and childlessness, a piece described by one commentator as an "eerie fusion of power and helplessness". While co-star Louisa Clein plays a mother full of the joys of childbirth and Lara Lemon plays a student who gives her baby up for adoption, McIntosh takes on the part of a woman who has suffered a string of miscarriages.

And that's what's turning her to bits.

"I just finished my divorce this year – rubber-stamped and everything," says McIntosh, whose six-year relationship with cameraman Xandy Sahla came to an end in 2006. "As the play goes on it becomes obvious that my character keeps losing her children. You've got the one for whom everything is nice, everything goes really well, and then you've got me going, 'Why can't I have a child?' So it's quite emotional. I was just a mess after the audition. Now I'm filling up again."

A couple of years ago, she told one newspaper how she had always wanted children by the time she was 35 and having kids was "definitely still on the agenda". Now, as she settles into post-divorce life, that desire makes her all the more empathetic with the unnamed woman in Plath's play.

But is it wise for her to be playing such a part at all? "Probably not," says McIntosh, who remains sitting upright, elegant and composed in spite of herself. "And that's a damned good reason to do it. I like to be honest and tell people about it, rather than wrapping everything up. Some people have a persona that they bring, and I can't do that. It's just me that you get, I'm afraid."

But far from being embarrassed, she sees this level of emotional engagement as part of the job. She recalls the set of Spring 1941, a 2008 film starring Joseph Fiennes that has been warmly received on the festival circuit, where the cast took the themes about the Holocaust very much to heart. This was doubly so in her case, because her own grandfather died of pneumonia in a Polish prisoner-of-war camp, having been captured in Dunkirk, and she made a poignant pilgrimage to his grave at the end of the shoot.

"We were all a mess when we came back. None of us could do anything for two or three months because we couldn't forget it," she says, welling up again.

Heart-on-her-sleeve she may be, but so too is she determined to portray women who are tough, feisty and in control. Whether it is as Donna Anna, a chaste obstacle in the path of Don Juan at Glasgow's Citizens' Theatre last year, or as Dr Kate Millar, a junior medic dealing with Douglas Henshall's unhinged Dr Daniel Nash in the 1999 series Psychos, she brings a cool authority to her characters. If it means turning down roles that show women as passive victims, it's a price she's prepared to pay.

"For a little while it felt that women (on screen] were just there as a bit of totty," says the actor, who was born in Paisley, brought up in Edinburgh and is performing on the Fringe for the first time since doing youth theatre as a 17-year-old. "The jobs that attract me are those where, yes, you can be the totty, but you can be something with a bit of gumption as well. Women are never the protagonists, we're always reactionary against everything that's done to us. I like people who write for women that have got a bit more about them. It means I have said no to stuff. At first, you go, 'Oh my God, I'm never going to work again,' and then you think, 'Well, no actually, that's not what I want to do.'" v

Three Women, Assembly Rooms, Edinburgh, 6-31 August www.edfringe.co.uk