If you ahve private health insurance, they have top class facilities for your wife. A hospital like the park Lane Clinic /Bedfordview Maternity Hospital /in Joburg has 1st World facilities and they would be able to handle any eventuality with regards to the birth and your wifes care.
Racial tension....well know one can guarentee that there will not be any. Normal the Indians would not have a problem, especially In Johannesburg and the predominant Indian Areas.