McCready spokeswoman Kat Atwood told ABCNews.com that the singer is entering her sixth month of pregnancy.
"She and the twins' father have been enjoying time spent out of the spotlight," she said. "Although they are excited in the baby news, they would 'like' to continue to do so in private at this time (as much as they can)."
The father is believed to be David Wilson, the man who spoke to police at an unoccupied lake home in Heber Springs, Ark., while the multi-platinum-selling recording artist was hiding in a closet with her son.
Even for McCready, who has struggled with addiction, depression, brushes with the law and a long custody battle over Zander, her latest troubles seemed to be a new low.
I cried and felt terrible for my sister when I found out that she had been hiding in a closet in someone else's home," Phelan said. "Although I don't agree with the things that she does, I will always love my sister, Mindy."
ABC News' Yunji de Nies contributed to this report.