The father is de Matteo's boyfriend, country singer Shooter Jennings, the actress' publicist, Amanda Silverman, said in an e-mail Tuesday to The Associated Press.
Silverman didn't provide further details.
De Matteo, 35, concluded her run on "The Sopranos" when her character was killed in the fifth season of the hit mob drama.
She also starred on the NBC sitcom "Joey" opposite Matt LeBlanc.
Photos: Celebrity Parents