The 30-year-old proved she had mastered maternity fashion when she showed off her baby bump in a monochrome striped dress back in October.
The mum-to-be beamed for photographers as she arrived at a star-studded party at London's Saatchi Gallery.
News that Melbourne-born Holly and her husband were expecting a baby emerged when photos of Holly's bump were published by Australian magazine Women's Day.
Only a month after their lavish LA wedding, Holly and Nick revealed that were already thinking about starting a family together.
"Finally at 30 I am coming round to the idea of babies and Nick, at 40, is well and truly ready," revealed the Kiss Kiss singer. "I think he might just get his way. I can see it now: I will be the bad cop – the strict one – and he will be the fabulous, fun dad!"