"If you guys don't know, I'm pregnant," Alba said as her fiance, producer Cash Warren, beamed. "You're all women. I think you understand your breasts are engorged and your stomach is getting bigger by the second."
Ensler founded V-Day, which now reaches 119 countries and has raised $50 million to increase awareness about violence against women.
"It literally started from one woman's voice ... and it's exponentially grown," Dawson, 28, said. "It's about embracing being a female and reclaiming that."
V-Day will celebrate its anniversary with a two-day event at New Orleans' Superdome in April.
Dawson, who is a V-Day board member, performed a poem about New Orleans, calling it "the vagina of America."
Katie Holmes, Val Kilmer, Kerry Washington, Ali Larter, Gina Gershon, Judith Light and Jennifer Beals also attended the event.
Cindi Leive, editor in chief of Glamour magazine, said last year's V-Day luncheon raised over $200,000.Holmes said her friend Paula Wagner - a longtime business partner of Holmes' husband, Tom Cruise - inspired her to become a part of V-Day.
"It's important for women to support each other and communicate with each other and be each other's friends," the 29-year-old Holmes said. "We should be working on stopping violence for people, for everyone."