The star announced on Twitter.com last month (Dec12) that she and husband Marc Silverstein are set to become parents for a second time, but Phillips insisted on honouring her TV filming schedule.
However, the actress admits her ever-growing bust caused problems on the set.
She tells U.S. TV host Conan O'Brien, ""What was great, we made the move to (cable network) TBS this year... we ended up shooting up until I was like 12 weeks pregnant so we were able to hide the stomach but I will say that my boobs grew three sizes in this season. So that's something fun everyone can look out for!""
The mother-to-be's co-star Courteney Cox recently appeared on O'Brien's show and revealed she planned to flash the flesh in the new series, but Philipps is adamant her own assets dominated the screen.
She quips, ""(Cox) had declared it the season of her cleavage... and then it ended up being my season of my boobs just expanding.""