Spanish actress Penelope Cruz was overcome with emotion, unable to hold back tears of joy when speaking at an interview about her baby boy and the delights of motherhood, Vogue magazine said Monday on its Web site.

Cruz, who will appear on the fashion magazine's cover for the fourth time in the June issue, said that being a mother "is the best thing in the world" and wept a little just thinking about Leonardo, born in January of her marriage to Spanish actor Javier Bardem.

"This has never happened to me," the actress said with tears in her eyes, one of the first times she has spoken publicly of her child.

"I want my son - and my kids if I have more - to grow up in a way that is as anonymous as possible. The fact that his father and I have chosen to do the work that we do doesn't give anybody the right to invade our privacy," Cruz said.

Cruz said there was a before and after in her life following the birth of Leonardo.

"It is a revolutionary experience," the 37-year-old actress said. "Nature is very wise and gives you nine months to prepare, but in that moment, when you see that face, you are transformed forever."