Gwyneth Paltrow's 'World of Tomorrow'

Sept. 17, 2004 -- On screen, Gwyneth Paltrow is saving the world from robot monsters. In real life, she's witnessing something more amazing — watching her 4-month-old baby grow.

"Everything is magical," the 31-year-old actress told Diane Sawyer Thursday on ABCNews' Good Morning America. "She rolled over for the first time."

Paltrow, who's married to Coldplay front man Chris Martin, confirmed reports that she sobbed for weeks after giving birth to her first child, Apple Blythe Alison Martin, born in London on May 14.

Those were tears of joy, she says.

"It's amazing because it was a whole new feeling that I had never experienced," she said. "The best way I can describe it is the most madly in love you have ever been mixed with the most painful heartbreak of all time.

"I just couldn't stop crying, every time I looked at her," she said, adding, "I'm sure some of it was hormones as well."

‘It Was Worth Every Minute’

Paltrow says she was in labor for more than 70 hours before giving birth to the 9-pound, 11-ounce child.

"We started having some trouble and they had to do intervention," Paltrow said. "It was a traumatic experience. I won't lie. But it was worth every minute. It's amazing. I came out of it thinking, 'Well, I would have amputated my legs for her.' So that [labor] was nothing."

This week, Paltrow graced the cover of Entertainment Weekly and attended the California premiere of her new film, Sky Captain and the World of Tomorrow, which opens nationwide today.

Paltrow wrapped up shooting Sky Captain about a year before the birth of Apple. She recently signed on to star in a biopic of legendary screen goddess Marlene Dietrich. Paltrow is no stranger to iconic roles, having portrayed poet Sylvia Plath.

In Sky Captain, Jude Law plays daredevil pilot Capt. Joe Sullivan, who joins forces with his on-again, off-again girlfriend, reporter Polly Perkins, to stop a mad scientist from destroying the world.

As Polly, Paltrow is Law's true love and worst nightmare. She's a news photographer who will do anything for a story — sometimes even at the hero's expense.

To further complicate matters, another ex-girlfriend of the captain comes along, in the form of Angelina Jolie.

Her Father’s Daughter

Law and Paltrow's characters are constantly bickering. Sawyer told Paltrow that Law wanted to know one thing: Where did Paltrow get her filthy sense of humor?

"I got it from my father because he was very irreverent," said Paltrow. "I think I picked it up from him."

In the fall of 2002, the death at age 58 of director Bruce Paltrow, famous for the groundbreaking TV series St. Elsewhere, sent the Oscar-winning actress into months of grieving.

Paltrow completed work in Sylvia, a role her father had urged her to take, but she cut back on other projects. She met Martin in 2003, and they married that December, spending most of their free time in London.

Now, as Paltrow steps back into the limelight, she's happy to do so as a mother, even if she put on 35 pounds during pregnancy.

"It's not all gone," she said of the weight. "A lot of it is in my upper half, serving multiple purposes."