The siblings, who competed as the Bella Twins in WWE wrestling, slammed reports during Wednesday's episode of their Bellas Podcast that they both underwent IVF so they could be pregnant at the same time.
"IVF is a major procedure. You don't just go in one day to the doctor and say, 'Hey, can I get some IVF?'" Nikki Bella said. "IVF is no joke."
Nikki Bella said becoming pregnant with IVF is as unpredictable as becoming pregnant naturally.
"Even if Brie and I wanted to do IVF and plan it, you can't even plan that at the same time," Nikki Bella said.
"You guys, it's so ridiculous. Brie and I both did not do IVF," she added. "We did not plan on being pregnant together."
Nikki Bella and Brie Bella announced in January that they are both pregnant and due to give birth within two weeks of each other. Nikki Bella is expecting her first child with her fiancé, Artem Chigvintsev, while Brie Bella is expecting her second child with her husband, Daniel Bryan.
"Wait, twins being pregnant at the same time? People are going to think that's a joke," Brie Bella told People at the time. "We both are shocked. People are going to think we planned it, but you can't really plan pregnancy!"
Nikki Bella said their pregnancies were a "total surprise."