The siblings, who performed in the WWE as the Bella Twins, said during a remote appearance Monday on Good Morning America that it's "bizarre" to be pregnant at the same time.
Brie is expecting her second child with her husband, Daniel Bryan, while Nikki is pregnant with her first child with her fiancé, Artem Chigvintsev. The sisters are due to give birth within two weeks of each other.
"We both were, like, really embarrassed," Nikki said. "It's just -- it's weird. We're identical twins, we're literally a week-and-a-half apart."
"We're next door neighbors," Brie added.
"It's just kind of weird," Nikki said.
"It's all bizarre," Brie agreed.
Brie and Nikki said they are experiencing the same pregnancy symptoms and food cravings. Nikki said the similarities have made her and Brie feel like they are expecting their own twins.
"It's so weird ... We have the same exact cravings, the same symptoms," she said. "We kind of feel like we're having our own set of twins. I know that sounds weird, but being a week and a half apart... We only each have one baby inside, but we feel like we're having our own twins."
Brie said her second pregnancy has been very different from when she was carrying her daughter, Birdie, who turns three in May.
"It's so weird for me to be exactly like [Nikki] but so different from my first pregnancy," she said.
Brie and Nikki again denied that they planned to be pregnant at the same time. The pair previously denied in February that they used in vitro fertilization to coordinate their pregnancies.
Brie and Nikki will release a memoir, Incomparable, on Tuesday. The book explores the sisters' lives and careers, including their time as WWE wrestlers.