The community rushed to the aid of the woman, who is 31 weeks pregnant, on Monday night.
Melissa Finch, 32, was walking downstairs when the concrete first-storey landing at Kimross Place, about a metre from the ground, gave way.
Her boyfriend and father of her unborn child, Ivor Geduld, 35, says he is shocked and upset as both Melissa and their baby could have been killed.
He blames the City of Cape Town for not upgrading the ageing flats.
Ivor explains Melissa’s injuries include deep tissue bruising on her right hand, arms and back, and there is a massive bump on the back of her head.
“We waited for an ambulance and rushed her to the Elsies River Day Hospital,” he says.
“The doctors checked her and she was taken to Karl Bremer Hospital for observation.
“She was confused and in a lot of pain. She could have died or could have lost the baby, but our homes won’t be fixed.
“The stairs have been broken for a while, but nothing is done.”
Melissa was discharged on Tuesday afternoon and says the baby is doing well, although she is still in pain.
“It could have been worse. I could have lost my child and I have to go to the hospital to check regularly if the baby is OK. I got a lot of medication and was told to get lots of rest,” the shy woman told the Daily Voice.
Resident Havelock Clarivette says the incident was deeply disturbing and could have been fatal.
“I have lived here for 44 years, since the day these flats were completed. Not once, no matter how many times we have asked, has the City come out to do any maintenance,” Clarivette said.
“Now this pregnant lady fell and the council will have to come fix everything, from the windows to the cracks in the walls, to leaking taps and the broken stairs.”
The City of Cape Town told the Daily Voice its Tenancy Management Department is investigating the matter.