Stables, who stars as Eden in The Exes, told People that she and Patino are very "happy" to be having a son.
The actress also confirmed that she is already busy getting her son's nursery ready even though she won't give birth until September.
Stables's pregnancy is expected to be written into The Exes' second season.
The Exes will premiere a new slate of episodes in June on TV Land.
Stables has also appeared as Melissa in Two and a Half Men and Janette in Greek.
Watch a preview of the second season of The Exes below (US only):