Tyra Banks Reveals Why She Can't Have Any More Kids (Exclusive)

Tyra Banks is getting candid about her difficulty undergoing invitro fertilization.

Tyra Banks is getting candid about her difficulty undergoing in vitro fertilization.

ET's Nischelle Turner spoke to the 44-year-old supermodel and her mother, Carolyn London, on Tuesday at BUILD Series studios about Banks' new book, Perfect Is Boring: 10 Things My Crazy, Fierce Mama Taught Me About Beauty, Booty, and Being a Boss, when she opened up about her decision to undergo IVF treatments in an attempt to get pregnant with her first child. In January 2016, it was announced that she and her boyfriend at the time, Erik Asla, had their first child, son York, born via surrogacy.

"Yeah, I don't remember if it was, 'Am I less than a woman?' but I remember just thinking, 'Oh my god, I waited too long, like, why did I do this?,'" she reflects. "Like, why did I do it? And I can remember, I was, you know, doing the rounds and stuff and then I create the embryo and I get the phone call, 'The embryo is not healthy.' You know, 'We can't move forward,' and just, like, just crazy for me -- just really, really difficult."

"I think I'm lucky, you know, I did it for about a year and a half of IVF and some women do it for years and years and years," she continues. "Unfortunately, I don't have embryos frozen because I want three kids. I think that was the end. I think I probably could've kept going, but I just think it wasn't healthy for my body because less eggs and less eggs and less eggs, you know, every month. But I'm so happy."

London remembers the heartbreak every time the treatment was unsuccessful, recalling that Banks already had a nursery set up.

"She made a tile and it said 'I love you already,'" London shares. "And then she went into, you know, the sessions and was not successful. And just to have to see her..."

"I think if I waited six more months I would not have him," Banks adds. "Yeah, I really do think that."

These days, Banks is clearly touched by the close relationship London has with 2-year-old York.

"Me and Nana and York, we get in the bed together, and it's like, wow, this is three generations, you know?" Banks marvels. "And we spend so much time together he now calls us Nana Mama."

Of course, London spoils York any chance she gets.

"Oh my god, it's amazing and awful," Banks jokes. "It's both. The amazing part is he loves her so much, like, they have this nightly ritual. I don't like to let him watch a lot of TV, but she says it's fine, like, 24/7 TV is fine for her. So, I try to say no TV. At night he's, like, 'Mommy, I'm going to Nana's bed. No, Mommy get out. Bye bye. Bye bye, Mommy.'"

The America's Got Talent host also talked to ET about her infamous "Kiss my fat a**" clapback at body shamers during a 2007 episode of The Tyra Banks Show.

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