Heidi Klum was pregnant with her daughter Leni during the 2003 Victoria's Secret Show.
The supermodel made the revelation in an Instagram post to mark her eldest daughter's 17th birthday, explaining that she was four months pregnant as she strutted her stuff on the catwalk.
Alongside a video from the event, Heidi wrote in the caption: "Happy 17th Birthday LENI.
"I am not alone in walking down that catwalk here.
"If I look close enough then I can see you bumping right along at 4 months @LeniKlum.
"I loved you before you were born, and I will love you long after I close my eyes forever. (sic)"
Heidi shares Leni with Italian businessman Flavio Briatore although he has not been involved in her life as the pair split shortly after her pregnancy announcement.
Klum went on to find love with the singer Seal and they went on to welcome three children together – sons Henry, 15 and Johan, 14, and daughter Lou, 11. The couple married in 2005 before splitting in 2012.
She has since gone to tie the knot with Tom Kaulitz, a guitarist from the band Tokio Hotel.
The 47-year-old model previously explained how her brood had to attend their online classes late at night when they travelled to Germany with their mother last year as she was working on 'Germany's Next Top Model' due to the time difference with their Los Angeles home.
Heidi said: "It's very hard for them. When I decided this could be a possibility that I'm doing the show in Germany, I asked all my kids and I said, 'Is this something you guys are even up for? Because we will have to go for quite some time.' They all wanted to go because we've been stuck in the house.
"It's just a nice change for them, but it's definitely hard for them because they are doing school in a different time zone. Again - thank you so much to the teachers, the schools around the world. They're making all these things happen that the brains of our kids can continue on learning and being those sponges that they need to be right now."
