The 29-year-old - who has previously starred in TV shows such as The O.C. and House - was spotted out and about in Venice Beach, LA, on Monday afternoon (6 January) and looked trendy in a low-key ensemble.
She teamed a pair of ripped light denim jeans with some brown boots and covered her just noticeable baby bump with a loose fitting T-shirt that featured the famous MTV logo.
Olivia also carried a brown satchel on her shoulder, donned a pair of sunglasses and pulled her hair up into a neat bun.
She and fiancé Jason Sudeikis announced in October that they are expecting their first child together, but the couple have remained quiet on any further details.
Film star Jason, 38, proposed to Olivia over Christmas in 2012, one year after they met during an appearance on US sketch show Saturday Night Live.
Most recently, the Hollywood couple were seen being blown away by illusionist David Blaine on his one-off special for Channel 4, Real or Magic.
Other guests on the magic show included Kanye West, Will Smith and Katy Perry.
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