Try Fedhealth or Medihelp. But your chances are slim, she is propably to far along! If Bonitas takes preggy ladies, then go for it!!
Betsa, usually medical aids accepts pregnant ladies but then excludes the pregnancy and birth from cover. Unless you are just switching from one medical aid to another, usually they don't have a problem with that. For interest sake, how far along where you pregnant when you joined Bonitas? And did you belong to another fund prior to that?
Gems is a goverment employees fund, so people are forced to belong to them, so they might accept preggy ladies, as the lady doesn't have much of a choice as to which medical aid she wants to join.