updated 09/16/2013 AT 11:00 AM ET
•originally published 09/16/2013 AT 1:35 PM ET
The mom-to-be appeared pool-ready, sporting a black strapless bikini with white lace trim.
“Going swimming with the kiddos,” she wrote in the caption. “This pool makes me feel so much lighter! This belly #twins #excited #blessed #nofilter.”
“I was completely shocked,” she said at the time. “I had no idea. It was a natural conception, but twins do run in the family, so I guess I shouldn’t have been surprised.”
Zolciak is married to Kroy Biermann, a defensive end for the Atlanta Falcons. The couple have two children together, sons Kroy Jr., 2, and Kash Kade, 13 months. Zolciak also has daughters Ariana, 9, and Brielle, 16.