The 28 year old faces one charge of concealing the body of a child.
She will appear in the Manukau District Court next month.
A post mortem was undertaken to see if the baby had died stillborn or after birth, but police said more testing needed to be done.
Section 181 of the Crimes Act makes it an offence for anyone to dispose of the dead body of any child in any manner with intent to conceal the fact of its birth, whether the child died before, or during, or after birth.