"@Biermann71 and I are soooo excited we are having another BOY!!! KJ will have a best friend for life!! Thank you for all the congrats," she tweeted.
She gave birth to her first son, Kroy Jagger Jr., last May. "Kroy and I are so excited to get pregnant again, and to have it happen so quickly was such a blessing," she said shortly after announcing the pregnancy.
The reality star has two daughters, Brielle, 15, and Adriana, 9, from a previous marriage.
Previously it wasn't clear if Zolciak would be returning for season five of Housewives. US Weekly reports that if the show is picked up, Zolciak will return. But she made it clear that her friendship with NeNe Leakes won't be improving anytime soon. "She has really changed," said Zolciak. "She's not funny to me anymore. She used to be really funny."