Shay Mitchell's partner has been left in ''awe'' of the way she's handled her pregnancy.

The 'Pretty Little Liars' star's partner Matte Babel is so thrilled to be having a baby with the actress and has praised her for her ''strength, vulnerability and grace''.

He wrote on Instagram: ''Watching the both of you grow over the past 6 months has been the most beautiful thing in the world. The strength, vulnerability and grace you've had during this pregnancy has left me in awe, you're going to be an incredible mom ... We're lucky to have you, love you.''

Shay kept her pregnancy a secret for six months before revealing the happy news this week.

Announcing her news on Instagram, she wrote: ''Does this mean I'm allowed to drive in the car pool lane at all times now? (sic)''

And in an accompanying video, Shay revealed it had been ''hard'' to keep her pregnancy a secret.

She said: ''When you're in the public eye, there are some things you want to just keep a secret until you feel ready. This, for me, has been the hardest. It's going to be really fun and awesome when I'm not trying to hide it anymore. I didn't want to come out on social media so early on. I'm going to be so happy when this comes out. I can be pregnant, like not suck my stomach in.''

And Shay's 'Pretty Little Liars' co-stars have been celebrating her pregnancy news.

Troian Bellisario - who welcomed a daughter with husband Patrick J. Adams in October - wrote: ''YAS queen, I am so excited to be a mama with you and welcome this beautiful babe to the world! (sic)''