A large blue ruffle adorns the door of the Rome apartment hotel, which in Italy signifies that a baby has been born. Upstairs the proud father, Ibrahim Moussa, 37, has barely finished explaining that the new mother is too weak from her cesarean childbirth to receive any visitors when Nastassja Kinski, 23, shuffles down the hallway, dressed in a dotted swiss nightgown and peignoir. Cradling their sleepy, 1-week-old son, Kinski does look a bit pale. The dark, haunted eyes that mesmerized moviegoers in Tess and The Hotel New Hampshire are underlined with shadows. The pregnancy was a hard one, and Nastassja was confined to bed for a month last spring for premature contractions. Since giving birth, Kinski has fainted several times. But when she speaks about her son, Aljosha Nakzynski Moussa (Nastassja had a German shepherd Aljosha in her childhood, and Nakzynski is a family name), she gushes with an uninhibited enthusiasm. "It's so wonderful," she says. "Now I know why I live. For the first time I have been proud of something I have done...Oh! Oh, he's smiling at me!"

Nastassja's maternal giddiness seems all the more endearing for being somewhat surprising. Her behavior during the pregnancy was anything but ordinary: The unmarried Kinski steadfastly refused to divulge the identity of her child's father. That reticence sparked a good deal of gossip, which reached its apogee when the West German magazine Bunte printed the names of eight alleged Kinski lovers, including actors Dudley Moore and Gerard Depardieu and directors Milos Forman, Wim Wenders and Roman Polanski. Kinski promptly ruled them out. Nor was there any confirmation forthcoming that Moussa—an Egyptian-born talent agent and film producer who has been her live-in companion for the last nine months—was the father. Now in the current euphoria, that denial has become inoperative. "Yes, it's true," says Moussa. "I am the baby's biological father." He could not acknowledge that before because Nastassja wanted it that way. "I didn't want anyone to sniff around my business. I decided not to say anything until the baby was born," Kinski explains.

Buoyed by her new candor, Nastassja also reveals that she and Moussa plan to marry soon. Both are already wearing gold bands on their left hands just to get into the spirit of things. But the relationship, Kinski explains, has not always been so intense. "We lived together like brother and sister in Ibrahim's house in Los Angeles while I was making the films One From the Heart and Cat People," she says. (Ibrahim was working for MGM and invited Nastassja to be a houseguest.) "That was two or three years ago, and over time we became closer and closer friends. It's hard to explain. It's not fireworks. It's a love earned through time and friendship. It's like the root of a tree that goes way down. I never felt like that with anybody."

For the moment, however, it is Aljosha who gets most of Nastassja's attention. She can happily spend 20 minutes discussing how to tie sorrisi (the Italian pinless diapers), and she is positively lyrical about breast feeding. "I am so proud that I can feed him myself," she says. "My chest is small, and I was worried that I would not have enough milk. But my breasts got huge and he gets lots of milk."

Kinski says she is anxious to give birth again: "I want two or three children, definitely." Ibrahim, in turn, is enamored of fatherhood and is giving up his film career for a more flexible job as an international representative for the Bulgari jewelry company. Nastassja will continue in films—but with a new attitude. "From now on I will try to choose good things and work very little," says the actress, who has made a dozen films in nine years. "I am not saying I am going to give it up. In fact, I think that now I can do really good work because it will be with a different attitude—full of life and joy and spirit." Pausing to cuddle her infant in his crocheted booties, Kinski continues her monologue on motherhood: "You have to adjust your life to the baby. That's the No. 1 thing. I know I have to try not to spoil him, but it's a natural thing to want to spoil your child." And then for a moment the flow of words stops. "Oh, God, he's smiling again!"