OMAHA, Nebraska (AP) — A Nebraska woman pleaded guilty Monday to burning and hiding a fetus after taking medication to end her pregnancy, while prosecutors are moving forward with a criminal case accusing her mother of illegally assisting in the abortion.

Prosecutors said Celeste Burgess gave birth to the stillborn fetus about 29 weeks and five days into her pregnancy. She was 17 at the time, but prosecutors charged her as an adult.

Burgess, now 18, pleaded guilty to concealing or abandoning a corpse, and prosecutors dropped two other minor misdemeanor charges. The fetus was found buried in a field north of Norfolk in northeastern Nebraska.

Her mother, Jessica Burgess, 42, is accused of illegally assisting in the abortion last spring. The prosecutor in charge said he had never before charged anyone with violating Nebraska’s 2010 abortion limit on 12-week abortions. On Monday, Nebraska Gov. Jim Pillen signed a law banning 12-week abortions. It went into effect immediately.

The charges against mother and daughter are based in part on Facebook messages the two women exchanged in which they described their plan to obtain a drug to induce an abortion and then burn the fetus.

Jessica Burgess has pleaded not guilty and is due back in court for a preliminary hearing on July 7. Her attorney did not immediately respond to a message Monday.

The sentencing for Celeste Burgess is scheduled for July 20. She faces up to two years in prison. The public prosecutor has agreed not to recommend a sentence.

According to court documents, in the messages the daughter exchanged with her mother, she talked about “how much she can’t wait to get that ‘thing’ out of her body.” In one of the messages, which investigators obtained with a search warrant, she also said, “I’m finally going to be able to wear jeans.”

In a message, Jessica Burgess told her daughter that she had obtained the pills and gave her instructions on how to terminate the pregnancy.

Last summer, a man pleaded guilty to helping the women bury the fetus.