The actress is one of the hosts on the red carpet Sunday at the Dolby Theater in Hollywood -- where the ceremony will be going down later today -- and before all the stars arrived to take their own pictures ... Vanessa made sure to steal the spotlight with shots of her own.

She had a very good reason, too ... clearly, Vanessa is expecting a child -- and this is the first time anyone's hearing about it publicly. On its face, it seems she's fairly far along.

Of course, this is major news ... seeing how this would be VH's first child, and ditto for her husband, Cole Tucker. Remember, they just got married a few months ago down in Mexico ... and now, they're having a kid together in record time. No time like the present, right?!

Cole and Vanessa have been together as a couple since 2020 ... after she broke things off with her longtime boyfriend, Austin Butler -- with whom she'd been with for many years.

Vanessa and Cole were two peas in a pod ... she said she knew he was the one right away.

While she's clearly happy with her hubby ... the topic of her relationship with Austin has come up quite a bit lately -- especially with him being launched into superstardom through all these movies he's been in the past couple years, including 'Elvis.'

Vanessa just said last week she's happy her split with Austin led her to Cole -- and Austin, meanwhile, has said he valued his time with Vanessa ... and still respected/cared about her.

Austin himself is not scheduled to be at today's Oscars ceremony -- although, he has been out and about for Oscars-related parties this weekend.

So, he might be around somewhere later tonight as well. Ya gotta wonder how he might feel about this big development.