The 30-year-old model has been dating 43-year-old Guy since April 2010 and they have a son named Rafael. This will be Guy's fourth child.
He shares a biological son, Rocco, 11, and an adopted son, David, six, with his ex-wife Madonna.
Guy and the singer split in 2008 after eight years of marriage.
Jacqui recently revealed she and her partner planned on expanding their brood. She said: 'I'd love more children. Guy and I have always wanted a big family. It's something we planned all along.'
Jacqui also revealed how Rocco and David love being big brothers to the baby and always want to help out.
She said: 'This is the first time I've been a biological mother but we've got the two big boys and they absolutely dote on Raph. They're always dancing with him and wanting to play with him.'