Lulama Cabela, 36, and Babalwa Cabela, 50, were arrested in February 2016 after a police investigation into illegal abortions in the city.
The pair operated from premises known as “Mother and Child Health Care Services” in Govan Mbeki Avenue, Central.
They were charged with 25 counts of concealment of birth after police discovered at least 25 foetuses in a freezer on the premises and convicted earlier in May in the regional court in Gqeberha.
Lulama Cabela offered both antenatal and postnatal services and Babalwa acted as her receptionist.
The court found that Lulama used both her Govan Mbeki business premises and her Cotswold home to perform abortions, some of them 13 weeks or longer after gestation.
SA law permits abortions within the first trimester of pregnancy.
After their arrest, the two women were released on bail of R5,000 each.
Sentencing has been scheduled for June 20.
In 2014, the Mother and Child Health Care Services operation made headlines when a 17-year-old was admitted to Dora Nginza Hospital, claiming she had visited the clinic for assistance with an abortion.
It was reported at the time that the teenager had been given pills to take, which led to her being admitted.