She may be an Oscar-winner and an accomplished actress but Halle Berry admits her latest role gave her challenges even she wasn't expecting.

As Audrey Burke in her new film, Things We Lost In The Fire, Berry plays a happily married mother-of-two whose life changes when her husband Brian (David Duchovny) dies. She then befriends his best friend Jerry (Benicio Del Toro), who is also struggling with his wildly-changing feelings.

Her performance is Oscar-worthy, as she explores all the wide expanse of emotions that Audrey feels, following her husband's death. The part also opened up her heart to her own impending real-life role as a mother. Halle, who is expecting her first child around March with boyfriend Gabriel Aubry, admits that her maternal instincts emerged during the shooting of the film.

The award-winning actress, who has won honours for 2001's Monster's Ball and 1998's Introducing Dorothy Dandridge, said: "I learnt that I need to be a mother through playing this role. I always thought that I did, I had that desire, but through playing this character, I really knew 100% that I'm meant to be a mother and that I have the ability to be a mother. I didn't really realise that in a way until I made this movie."

Working with the two on-screen children made Halle more aware that she had what it takes. "I think I have a way with children and that I really had to understand these children in this movie in a new way that I never really expressed before," she explains, touching her stomach.

"When children are dealing with grief and loss and with difficult situations, I think that, as a mother, you're the one that protects them, that makes them feel safe. You're responsible for their emotional and physical well-being and it's a heightened situation. I really learned that I think I could I do that, that I'm made up of what it would take to be able to really protect my children and I think that's a key element to motherhood."

However she realises it can be a struggle. "Motherhood is tough, it's the toughest job I'll ever do, this I know. But I also know that I'm up for the challenge and I think that I'm really ready, I'm at a good time in my life. But it's not easy at all."

Halle also found working on the film moving in other ways. "Many many days I got affected - and not even the days that one would think," says the twice-married actress.

"I was wanting to be a mother, so of course I connected to that. But I also connected to the idea of these two people, two friends coming together, who were at odds, who heal all of their internal wounds and help each other to become better people. As a result of this tragic event they come out better at the end of the day and that was inspiring to me.

"The crying scenes are the easier things to do in a way because you know exactly what you need to do so it's very clear. It's the little scenes where you're not really sure what they should be and how do you actualise or verbalise what you really want to say that are more difficult.

"Those moments that weave the movie together were, to me, a lot harder to figure out than the big scenes that are very clear what they are and what they are meant to be."

It was a role she wanted, but was initially concerned that she might be passed over, as she admits one of her biggest fears is being discriminated against because of the colour of her skin.

"When I first read this script, I said to my manager, 'I just have to do this movie'. But I didn't think I was right for this part, just because it wasn't written black," she says with a wry smile.

"Audrey wasn't written as a black character, so I wasn't the first thought on anybody's mind. I hoped maybe they would be able to see outside the box. My biggest fear got put to rest when I realised the director Susanne Bier did not care one ounce about the colour of my skin. When you meet someone like her, who is void of those thoughts at all, it really is like a dream come true."

And the 41-year-old former beauty queen is intent on making a change. "I want to seek out directors like her, producers and movie studios, executives like her who really are thinking in the 21st century and aren't laden of those old ignorant thoughts of the past," she says. "It is a new day and it's time we started addressing these issues because it's kind of ridiculous."

Despite her popularity and star status, Halle reveals she had to fight for the role.

"I think most actors have to fight for the good parts. They're so few and far between, especially for women. I very rarely read scripts with roles for women that are this good and this needy and this deep, and when I read this script, I connected with the material."

Halle, who has tackled serious roles in the past, wasn't put off by the challenges.

"It was a bit scary, which is why I really wanted to do it. As Susanne said, I didn't have a basis for it. I had never really lost someone close to my life that I was really close to, so I didn't really understand the stages of grieving or what happens when someone dies.

She continues: "All of those things really made it exciting for me to want to dive into. I've always done risky roles since the beginning - I played a crackhead in my very first movie [Spike Lee's Jungle Fever] - and I think I'll always continue to do that. That's the joy of it for me."

So while the half-British star is looking forward to the next stage in her personal life, she insists work will always be a part of her life. As well as acting, Halle is moving into film and TV production.

"I'll never stop working, and as long as I can work, I will be working," she admits.

"I've been off since I've made this movie and I'm going a bit batty, so no. I think I'll be back to work as soon as I possibly can get myself together."

But right now, Halle's sights are set firmly on motherhood.

"That's my greatest and my next biggest challenge. And I think it will be the best accomplishment of my life. I'm really looking forward to it."

Name: Halle Maria Berry

Age: 41

Significant other: Boyfriend is French-Canadian model Gabriel Aubry

Career high: Being the first African-American actress to win an Oscar for Best Actress in 2002

Career low: Her portrayal of Catwoman won her a Razzie award for Worst Actress

Famous for: Baring all in Swordfish and Monster's Ball

Words of wisdom: "I want to be the next Spike Lee. I want to help other black folks to get into Hollywood and be successful in Hollywood."