Posting a photo of the longtime couple taken soon after their daughter, Alexandria "Lexi" Zahra Jones, was born in August 2000, Brinkley, 61, recalled how she had helped her model friend, 60, to conceive.
"Iman always told the story in such a charming way," Brinkley wrote on Instagram. "'It took two blondes to get me pregnant David Bowie and Christie Brinkley!' 'You see...' Iman explained to me, 'in Somalia they say if you are having trouble getting pregnant you must hold a baby all day' so I handed her my baby, Sailor, and she held her all day long ... and sure enough, it worked!"
Brinkley continued, "After 7 years trying without luck ... Iman got pregnant! So beyond her great beauty and business savvy, and beyond Bowie's music and art, I always felt a sweet connection to this stunningly gorgeous and creative couple."
She added, "Today my heart aches For Iman, and Alexandria for their untimely and unbearable loss. My deepest sympathy @the_real_iman."
Bowie, who was married to Iman for nearly 24 years, died at the age of 69 after battling cancer for more than a year.
His connection with Iman was immediate, according to a biography of the singer.
"I was naming the children the night we met," he gushed. "I just fell under her spell."