Taylor Parker -- the Texas woman convicted in the shocking "Maternal Instincts" murder case -- is heard claiming to cops she just gave birth to her child, moments before officers realize the darker story.

Parker's chilling encounter with law enforcement is back in the spotlight ... and in the complete, uncut 911 audio obtained by TMZ from Bowie County court, the convicted killer is heard insisting she's going into labor on the side of the road.

Parker told officers and the dispatcher she had delivered a baby in her car, and was desperately trying to get medical help. At the time, cops had no idea they were stepping into one of the most disturbing murder cases in recent memory.

Investigators would later determine Parker had been faking a pregnancy for months and concocted an elaborate scheme to convince friends, family, and her boyfriend she was expecting ... before things turned fatal.

Authorities say the story unraveled after medical personnel quickly realized Parker had not recently given birth.

Prosecutors said Parker murdered her 21-year-old friend Reagan Simmons-Hancock -- who was more than eight months pregnant -- and removed the unborn baby before fleeing with the child. The infant later died.

Interest in the 2020 case has surged again following the release of Netflix's "Maternal Instinct" ... which features some of Parker's unhinged 911 call. The documentary details the shocking events leading up to her arrest after lying for months to her boyfriend Wade Griffin, and her entire community about being pregnant.