Katherine Heigl: Life as Hollywood's most criticised woman

"When somebody says something negative about me I have a tendency to think, 'They must be right! I must be an asshole!' but I think age has helped me deal with criticism," the perpetually criticised Katherine Heigl tells news.com.au.

"I didn't deal with it well in my 20s. I was so self-conscious and self-doubting, and even now, it's hard not to care when you feel judged unfairly." She shrugs her shoulders.

"I have to be honest, I'm a very neurotic person, but just growing older has lessened that feeling of shame."

Heigl has been picked apart since 2008, when she made headlines after criticising her own film in Vanity Fair, saying she thought Knocked Up, was "a little sexist." She was also at the centre of some well-documented blow-ups with Grey's Anatomy writers, with the showrunner Shonda Rhimes finally letting her out of her contract in 2010.

"At a certain point, I had to think, 'Who do I really, really want to like me?' and that question saved me because there aren't many people. I want my husband to like me, my family, and I hope one day my children will like me. I'm always grateful for the support of fans. I'm always grateful for the support of the press but I don't need it to the point where now it debilitates me if I don't have it."

"All of that is easier to take since becoming a mum. I have a better perspective because my life became so much bigger than just worrying what people think about me. Up until then, my life was my career, but I have distance from it now."

Fed up with Hollywood, she moved to Utah in 2010, with husband, musician Josh Kelley, 36, to raise their adopted daughters, Naleigh, 7, and Adalaide, 4. They reside on a secluded 25-acre ranch, an hour's drive from Salt Lake City.

Heigl is back in Los Angeles to promote her upcoming TV drama, Doubt. She's proudly revealing her baby bump and is due to deliver her first biological child, a son, in January.

Now that the star is finally knocked up herself, is she nervous about the big day?

"I'm not nervous but I'm only 20 weeks pregnant now. I have this inkling that I will become nervous as it approaches but there's nothing I can do about it now," she laughs, patting her stomach.

"It's done. So I can't worry about it. Millions of women have done it so I'll be all right." She leans forward. "Although I will be asking for an epidural a week before."

Unlike her character in Knocked Up, who was plagued by morning sickness, Heigl has had a different experience.

"It's been a relatively easy pregnancy. I feel great. I don't feel pregnant, I just feel chubby and that's hard as an actress in Hollywood. You work so hard and so diligently to not feel that way and not to look that way, and now all I want to do is eat!" She laughs.

"So, I've just had to surrender to this whole experience. But now I can feel him moving, which is amazing." She grins at Kelley, who is sitting at the back of the hotel room during our chat.

"We weren't really planning this. I thought, 'We'll see what happens', kind of thing. I'm 37 and didn't know if I could get pregnant, I've never been pregnant before. You reach an age where people scare the crap out of you, 'You gotta get going! The clock is ticking!'"

What do her daughters think of the impending addition to the family?

"They're thrilled. Adalaide wanted a sister because she wants someone to boss around - because Naleigh bosses her around - but Naleigh's excited that it's a boy."

Heigl is one of four children, one of whom was adopted from South Korea. Due to this family dynamic she felt compelled to mother a child (Naleigh) from her adoptive sister's birthplace. Adelaide, however, was born in the US.

Despite Heigl's "difficult" image, the fact that her eldest daughter is a special-needs child (born with a heart defect), speaks volumes in her favour.

"I couldn't have done it without Josh. We were very blessed in that Naleigh's needs were minimal and easily cared for. At the time of her birth, and then again when she was three months old, she had open-heart surgery, but she is perfect and in perfect health." She grins. "We're very blessed."