Naomi Tekea Craig, 33, on Tuesday pleaded guilty to 15 counts of indecently dealing with a boy, now 13, including 10 counts of sexual penetration of a child.
Police believe Craig, from Mandurah south of Perth, gave birth to the boy's child following the alleged incidents between 2024 and 2025.
She appeared in the Mandurah Magistrates Court via audio-link and entered guilty pleas to all the charges before her case was "fast-tracked" to the District Court for sentence mention on March 27.
The magistrate extended Craig's bail with strict conditions, including no contact with the boy and no unsupervised contact with any children other than her baby, born on January 8.
The court heard that Craig was excused from appearing in court in person on Tuesday due to a medical condition, but magistrate Clare Cullen told her this could not be extended to her next appearance.
WA Police previously said Craig engaged in persistent sexual conduct with the student.
"At the time of the commencement of the alleged offending, the woman was a teacher at a school in the Mandurah District, and the male youth was a student," a spokesman said.
Craig was initially charged with four offences in December before prosecutors laid an extra four charges last week.
An additional eight charges were laid before she appeared in court on Tuesday, including five counts of sexual penetration of a child under 13 and indecent dealings with child under 13.
Western Australian Police Commissioner Col Blanch has said a DNA test had been conducted after Craig gave birth and it was believed the victim was the father.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
42°C