Her brother, Brendan Gow, said that the baby was due in February. The father is Arpad "Arkie" Busson, the 35-year-old Swiss financier who has been at MacPherson's side since she split up with Kevin Costner, the Hollywood star, last year.
Mr Gow said that the model had told her family about the pregnancy a month ago. "She's very, very happy, and it will be a very welcome addition to the family," he said. According to reports in Australian women's magazines, MacPherson has been wearing an engagement ring since March, but has told friends that she does not plan to get married until after the baby is born.
Her father, Peter Gow, said yesterday that she had been "in love for some time now". He added: "I don't know about marriage. This is the 20th century."
In recent years, MacPherson has branched out from her lucrative modelling career into other interests, including acting. Coincidentally, her latest role is as an expectant mother, complete with padding, in the American film Mom's Up On The Roof.
MacPherson, whose previous credits include Batman and Robin and Sirens, also has her own women's underwear label, Elle MacPherson Intimates, and a share with fellow models in the Fashion Cafe, a chain of theme restaurants.
Her relationship with Mr Busson follows a string of romances with wealthy and high-profile men including Yann Gamblin, the French photographer, Tim Jefferies, the British multi-millionaire art dealer, actor Sean Penn and the rock star Michael Hutchence.
She married a French photographer, Gilles Bensimon, in 1986, but they separated six years later when she found out that he was having an affair with another model.
MacPherson can still charge tens of thousands of pounds a day as a model, but there are those happy to report any less-than-perfect physical attribute. One newspaper gleefully reported signs of cellulite when she was photographed on holiday in St Tropez last month.Reuse content