"When you breastfeed, for some reason, you lose a lot of hair, especially on the sides," Brie Bella tells PEOPLE
Nikki Bella, Brie Bella
Nikki and Brie Bella
| Credit: Randy Shropshire/USA Network/NBCU Photo Bank/NBCUniversal via Getty

Nikki and Brie Bella are getting real about their postpartum journey — the good and the bad!

In an exclusive interview with PEOPLE, the Total Bellas twins, 37, shared some very real details about their experience with hair loss during and after pregnancy, and why they're so thrilled to finally launch their Nicole+Brizee haircare line, Tearless.

"I did warn Nicole, I'm like, 'When you breastfeed, for some reason, you lose a lot of hair, especially on the sides,' " said Brie, who welcomed 7-month-old son Buddy Dessert on Aug. 1 and shares 3-year-old daughter Birdie with husband Daniel Bryan. "I go, 'Your hair grows fast, but you also lose it in these two spots.' "

"And the eyelashes," added Nikki, who welcomed son Matteo on July 31 with her fiancé, Artem Chigvintsev.

"And the eyelashes," agreed Brie. "It happened to me with Birdie and then literally the day I stopped breastfeeding, it just stopped. It's bizarre. And it happened in the exact same spot to Nicole."

"Yeah. And very little, I still do a prenatal every day and someone told me, 'Stick with your prenatal every day while breastfeeding.' So I'm really good with that. I feel like my hair's just thick, but then it does have those spots around that just are kind of missing, and then my eyelashes are gone. I look at Matteo's eyelashes and I'm like, 'You took mommy's eyelashes.' "

Nikki and Brie Bella
Credit: Brie Bella/Instagram

In February, the former WWE pros announced the newest expansion of their beauty line Nicole+Brizee, Tearless — a new haircare line specifically designed for babies.

"After having the boys together, we really wanted to start to get into baby products with Nicole+Brizee," said Brie. "For us we're moms and I have Birdie, who's almost 4, so having baby products is in our everyday life. So we're like, 'Nicole+Brizee needs to jump on board with this.' "

"Plus with our mother having emergency brain surgery last summer, one thing we'd never realized is my mom had just started using Tearless," the mom of two added. "So if you've had eye surgery, my mom with her brain surgery, they recommend you use tearless shampoo. So Nicole and I are like, 'Oh, we got to do this.' So it really inspired us to create our own line."

RELATED VIDEO: Nikki Bella Shows Off Post-Baby Body 5 Months After Son Matteo's Birth: 'Getting There!'

"And to add on to that, where I think we are so unique, adults can also use the shampoo and conditioner at the same time a baby can use shampoo and the shampoo is also made for a body wash," Nikki said.

"I just think of everything I have right now in my bathtub or my shower," she added. "It's so nice knowing that on Matteo, I can use this one bottle for him fully, and then mama can use it on herself and not get dried out hair, actually hydrate my hair and have an incredible conditioner that goes with that as well as if I have a toddler who has curly hair, always has knots, they benefit from it as well. And I don't think there's any line out there that's done that yet."