The reporters, Krystin Lisaius and her husband Somchai Lisaius, filed the plea Wednesday.
The couple faces up to two years in prison or probation. The child abuse and drug charges previously filed were dropped, according to CBS News.
"You both agree that your behavior was reckless by using cocaine and then knowingly — you, of course, Ms. Lisaius — breastfeeding the child the next morning, that constituted endangering the child, recklessly endangering her?" asked Pima County Superior Court Judge Howard Fell, according to News Channel 10.
The couple's lawyer, Mike Piccarreta, said his clients have been working to make things right.
"They've been going through regular drug testing. They've been going through parenting classes. They have gone through counseling... Anytime anyone even hints they want something done, they step up and do it," he told News Channel 10.
In May, the couple rushed their baby girl to a hospital after she began to act lethargic.
According to an Oro Valley Police report, the couple said their baby was also not eating normally, but they refused to allow hospital staff to draw blood from the child.
The couple then left the hospital with their baby against medical advice, according to the report, before going to a second hospital.
At the second hospital, police say the couple was again uncooperative when asked to take a blood sample from the infant.
However, hospital staff told police that a urinalysis was conducted and it reportedly confirmed the presence of a drug, the name of which police have redacted. According to multiple reports, the drug was cocaine.
After first denying she'd used cocaine, police say Mrs. Lisaius eventually admitted to doing the drug the night before at a barbecue she and her husband had hosted at their home.
She also allegedly told a social worker that she'd been breastfeeding the child but that she thought it would be safe to do so after 12 hours had elapsed since she last used the drug.
Police said in the report that Mr. Lisaius also admitted to using cocaine with his wife and a friend at their home.
The couple admitted to having cocaine in their home, as well, and directed police where to find it, the police report says.
On June 9, 2016, the parents were indicted on possession of a drug, drug paraphernalia and child abuse charges.
The child has been placed in the custody of a family member.
As footage by KVOA shows, they appeared in court for the first time Monday, where they pleaded not guilty to all three felonies.
Piccarretta told reporters that this was an isolated incident and that he's confident the baby will be back in the Lisaius' care soon.