A pregnant Isla Fisher makes sure that she and her baby are healthy as "The Great Gatsby" went on one of her regular hikes in Los Angeles on Sunday.

Isla Fisher is pregnant with her third child with "Borat" star Sasha Baron Cohen.

"The redhead beauty - who celebrated her 39th birthday on February 3 - was seen rubbing her bump as she donned a white, wide-brimmed hair while going for a hilly stroll with a pal," said Daily Mail.

"Wearing a loose-fitting black-and-white checked shirt over a white T-shirt, the Wedding Crashers star donned a pair of black cropped leggings under a matching mini-skirt," it added.

The pregnant star's casual look was a stark contrast to the elegance she exuded during the Vanity Fair Oscars after party. Isla Fisher wore Tony Burch floral-printed dress with her baby bump clearly showing.

Jennifer Aniston couldn't help but give Isla Fisher's baby bump a kiss while hamming it up for the camera.

Speaking to Fitness magazine vial Daily Mail earlier, the pregnant Isla Fisher said, "I gained 65 pounds (30kg) with my first baby and 70 (32kg) with my second. I had severe morning sickness both times, so I mostly ate supersize bowls of white pasta with loads of butter and cheese because that was the only thing that took away the nausea."

On Feb. 3, the pregnant Isla Fisher celebrated her 39th birthday with a cooking lesson attended by her family and closest friends.

Us Weekly reported that the cooking lesson composed of a very select group, and the attendees learned how to make appetizers, fish, dessert composed of four courses.

"It was a very hands on class with unlimited alcohol," the source told the magazine. "Everyone had a really fun time, it was a great group."

At one point, the group ran out of champagne, so somedowy went out to get more bottles and the cooking lesson/party continued on to the night.