Life as Little Mo

Kacey Ainsworth sinks into the sofa and sips carefully from a mug of hot water and milk. "This is another of my weird pregnancy fads," she says, smiling. "If I decide I want something, I have to have it at once. But as soon as my boyfriend buys a bag of something like Alpen, I've already gone off it."

She lifts her baggy black cardigan to reveal a football-sized lump sticking out of her diminutive frame. "Yep, it's definitely there. I don't know if it's a girl or boy, though. It's due at the end of April, so whatever it is, it will be a Taurus."

We meet at Elstree studios, where she has spent her last day filming EastEnders before disappearing on maternity leave. She is excited, nervous, emotionally exhausted. "This is such a precious pregnancy," she says, touching and shielding her stomach absentmindedly. "I was terrified of losing the baby again."

Last year, she miscarried at two months - her baby's heart was growing outside its body. Although she acknowledges that, as a soap star watched by 17 million people four times a week, her life has become public property, she found it terribly painful that her heartache was suddenly front page news.

"The worst situation was when people had read about me being pregnant, but not that I'd lost the baby. They would come up to me and pat my tummy, congratulating me. That was really tough. I had to tell them what had happened and they just didn't know what to say in response."

She pauses. "It wasn't always like that, though. I also found it very comforting, because people would tell me about their experience of miscarriage while standing there with three kids. That offered me hope. It was so important to share my experience because when you miscarry you feel like a failure. Your job was to nurture the baby and somehow you did something wrong."

This time around, everything is going really well: mother and baby are healthy, and she is well past the four-month mark. But it was during this pregnancy, and also at the point when she was exactly two months pregnant, that Ainsworth had to film the most traumatic scenes of her career - a storyline that culminates in a brutal rape, to be screened tomorrow evening.

"Working on a rape scene was hard enough," she says, "but being in the early stages of pregnancy made it doubly bizarre." She takes a breath and smiles. "I talked with my bosses to work out the best way of handling the scene - I couldn't risk bawling my eyes out. And I talked to a counsellor about the effect the acting [the inevitable physical trauma and distress] would have on the baby. We discussed foetal trauma and did a lot of talking to the baby. We also decided that any time I wasn't filming had to be really nice. My boyfriend made home life lovely; I'd come home to dinner on the table, the house smelled lovely. My mother cooked comfort food. It really helped."

Ainsworth, 35, has been with her partner, Darren Hales, for almost seven years: although they dated briefly when she was 15, she found him cheating on her in the back of a Ford Cortina.

It seems the couple have been through some difficult times that have brought them closer. When she got back together with Hales, a plumber, in the mid-Nineties, he became increasingly aware that she was suffering from anorexia nervosa and helped her to overcome it. He broke down in tears one day and told her that she was wasting away in front of him.

The seeds of her condition were sown when she was nine and appearing in the West End musical Annie: someone told her she was fat, and it stuck in her mind. She also thinks she might be prone to obsessive behaviour: her father had been an alcoholic. She over- exercised, under-ate and became obsessed with weighing herself. She was just seven stone when she joined East-Enders in spring 2000, when she admits that the ideal weight for her 5ft 2in frame is closer to nine stone.

She thinks her problems with food are now over, and is ensuring she eats well for the health of the baby.

The couple live with their two boisterous Labradors in a barn conversion in Hertfordshire, within commuting distance of the EastEnders set. They are engaged, but Ainsworth shrugs when the subject of marriage comes up. "There is no rush. Darren would probably like to get it done and dusted but I haven't really got that burning desire to be princess for a day." She rubs her tummy. "I'm certainly not going to be waddling down the aisle."

As the soap films around two months ahead, Little Mo's storyline will run until the end of January.

There has already been some criticism about Mo being subjected to even more sexual abuse - she was raped by her estranged husband, Trevor, two years ago - and suggestions that it is a cynical ratings move. Such responses infuriate her.

"I received so many letters from people who were, or who had been, victims of domestic violence. There were helplines at the end of the episode. It really seems people were helped by what happened to Little Mo. It gave them strength. I even heard that a video of EastEnders was used in a court case of domestic violence. That's stunning."

After her domestic violence storyline became a national talking point, the public became more familiar with the shocking statistic that one in four women in Britain are affected. And Kacey herself has since become an unofficial spokeswoman for Refuge, a charity which provides support to women experiencing domestic violence. She feels very strongly that it is important for people to be aware of the facts about rape. "Have you noticed how many high-profile rape cases are being reported in the papers just now?" she says passionately. "It's not something that's going to go away. And this is the time of year when women are more vulnerable than ever, too, with all the Christmas parties coming up."

The message that EastEnders is hoping to make clear this Christmas is that rape is most often committed by someone you already know.

"It could very easily be a flatmate's brother's friend. It's generally not a matter of being bashed over the head and dragged into a bush by a stranger. The key word, I think, is 'consent' - wearing bugger all in a nightclub is not consent. Neither is having a drink with someone, going to their hotel room or even kissing them. Consent is only when two people agree to have sex."

When Ainsworth took on the role of Little Mo after training at London's Central Drama College - she grew up in north London, and her first career was in advertising - she hardly expected her character would be one that would make a difference.

She laughs. "No bloody clue! Not at all. It's been very odd. I certainly didn't envisage myself doing talks for Refuge, or launching the domestic violence unit helpline in Hertfordshire. If I can help, I will help."

Of course, as Little Mo's story airs, Ainsworth herself is about to disappear from the public eye to prepare for motherhood. She straightens her back. "I shall probably drive Darren nuts sitting at home all day. I'm so used to working 12-hour shifts, having just two hours to catch a friend or see the family. Now I have some quality time with everyone." She smiles. "But I'm sure I'll miss the buzz, too. It won't be too long before Little Mo is back."

EastEnders is on BBC1 on Tuesdays and Thursdays at 7.30pm, Mondays and Fridays at 8pm; the omnibus is on Sundays.