Ka Yang, 29

Ka Yang, 29 (Booking Photo)

SACRAMENTO (KTLA) -- A mother charged with murder after allegedly 'cooking' her baby in a microwave is reportedly pregnant again.

At 29-year-old Ka Yang's arraignment on Thursday morning, her longtime friend said Yang is four months pregnant.

Yang apparently did not no she was pregnant when her daughter was found dead in March. She found out after the incident, according to the friend.

Yang did not enter a plea at Thursday's hearing. Her attorney told the judge they were still collecting evidence.

She faces one count of murder and one count of felony assault resulting in the death of a child.

On March 17, police were called to Yang's home to reports of an unresponsive baby. The 6-week-old girl, named Mirabelle, had suffered extensive thermal injuries.

Yang was not taken into custody until June 21, Sacramento Police spokesman Sgt. Norm Leong said.

Leong said it took several months to determine the child's burns did indeed come from a microwave, using medical analysis and findings from three other U.S. cases.

Yang told police she suffered a seizure while holding her daughter, and woke up with the girl on the ground next to her.

However, an autopsy determined the infant died of "extensive second-, third- and fourth-degree thermal injuries."

Child welfare workers removed Yang's three boys, who are all under age 7, from her home, Leong said.

Sacramento police said they do not know what would have led Yang to allegedly put her baby in the microwave.

Friends told FOX40 Yang always wanted a girl and waited years to have one.

Yang is being held without bail.

Her family says they are worried about her health in jail.

Yang is prone to seizures, and has been having more since she's been in jail, her mother told FOX40.