While preparing for the birth of her baby with Brad Pitt, Angelina Jolie has stepped up a campaign to save the lives of mothers, fathers and children in Darfur, Sudan.

Jolie, 30, a United Nations goodwill ambassador, plans to take out a large advertisement in USA Today on her own accord next week, explaining in her words the past killings of 400,000 civilians by the Sudanese government-supported militia Janjaweed and the need to stop the violence.

"I chose to take out this ad because when Congress returns from recess (on April 24) they have the chance to fully fund peacekeepers in Darfur," Jolie tells PEOPLE. "The situation in Darfur has been going on far too long. It¡¯s only getting worse. Reports are pouring in about mass atrocities including children getting raped and killed. If people are aware of the facts, I believe many will be driven to action."

Jolie, who notes in the ad "I'm an actress, and certainly no foreign policy expert," has visited the region twice ¨C once in October 2004 and again in June 2004.

She asks those interested in the campaign to visit the Web site www.genocideintervention.net.

Although she's eight months pregnant and presently staying in Namibia with Pitt, 42, and their kids, Maddox, 4, and Zahara, 1, "she's right there personally e-mailing, dictating, giving creative input," says Trevor Neilson, who works as a philanthropic adviser to Jolie and Pitt. "This project is her vision, her concept."