The "Sex and the City" star and partner Christine Marinoni welcomed a son, Max Ellington Nixon-Marinoni, on Monday, February 7, Nixon's rep confirms to People.com.
Marinoni gave birth to the couple's son, their first child together.
"Christine and baby are doing great," her rep tells PEOPLE.
Nixon and Marinoni began dating in 2004 and were engaged in April 2009.
This is Nixon's third child; she has two other children, Samantha, 14, and Charles, 8, from her previous relationship with photographer Danny Mozes.