Credit: GSNY/PPNY/Splash News Online

Mama Swan is out of hiding!

New mom Natalie Portman finally resurfaced in NYC on Thursday. Walking her dog near the Tribeca apartment she shares with fiance Benjamin Millepied, the Oscar-winning actress, 30, stayed casual and covered up in a long sleeve shirt, sweats, and sneakers -- flashing her famous grin as she adjusted her sunglasses.

Portman and Millepied have kept a super-low profile since welcoming their first child, a son reportedly named Aleph, in early June. She and French-born dancer/choreographer Millepied, 33, met on the set of Black Swan last year, and announced their engagement -- and her pregnancy -- in early January. See more pics of Natalie's post-baby body.

Little Aleph takes his name from the first letter in the Hebrew alphabet; the name also represents the "oneness of God" and the element of air. Jerusalem-born Portman has dual American-Israeli citizenship.

How did Portman keep up a fitness routine while pregnant? "I have been swimming every day," she told Us Weekly at the Oscars in February.