In a court filing, Child Protective Services says the teen produced a baby purported to be her biological child for genetic testing in January. But tests revealed she is not the infant's biological mother.
State officials believe the girl was married to a man in the Fundamentalist Church of Jesus Christ of Latter Day Saints when she was 14. In Texas, someone younger than 17 generally cannot consent to sex with an adult.
FLDS spokesman Willie Jessop says the girl previously said she feared the agency would try to take the infant.
A hearing in the teen's case is scheduled for Friday.
Slideshow archive | ABC13 wireless | Headlines at a glance