An Australian woman has given birth to naturally conceived identical quadruplet daughters, all sharing the one placenta and split from a singular fertilised egg in one of the few known cases of its kind in the world.

Jenitar Sau Na’amoana, 34, was raising four young children and had not planned to have another when she naturally fell pregnant.

It's being considered one of the rarest births in the world, a Brisbane mother delivering identical quadruplet girls who were naturally conceived.