Kelly Cook and Ian Hutchison's baby girl Ava was deemed to be at 'serious risk of harm' and they had to move in with Mr Hutchinson's mother to prevent her being taken into care.
Despite the seriousness of the accusations, the couple say it was a full nine days before social workers visited again. When they did eventually see the new parents and Ava it was decided that the mark could not be a bruise as it had faded then reappeared.
Kelly and Ian were allowed to return to their own home with Ava a week later, when the case was closed after a dermatologist confirmed the mark was not a bruise.
Legal secretary Kelly, 31, said the investigation into them made 'no sense'.
"We were effectively housebound – we couldn't go anywhere without Ian's parents," she told the Metro.
"Yet we cannot understand why – if they were so worried about Ava – no one came to visit us. Neither of us have ever been of concern to the police or had any dealings with them. It makes no sense."
She and Ian, 35, have complained about the incident to their city council in Southampton.
Ava is now waiting for a follow-up dermatology appointment to get to the bottom of what is causing the mark on her foot to appear and disappear.