The Saturdays singer announced her pregnancy in May just a few weeks after the couple revealed that they were engaged.
After posting an image of baby boy clothes on her Instagram account, Sandford said: "Having so much fun getting my little dude's clothes together! A little boy to add to the @thesaturdays crew! Can't wait to meet the cheeky monkey!"
Bridge's newborn will be a half-brother for six-year-old son Jaydon, whom the ex-Chelsea player fathered in a previous relationship with Vanessa Perroncel.