ANACONDA, Mont. -

Law enforcement officers in southwestern Montana are looking for a woman who fled the Anaconda hospital after giving birth to her son while under the influence of methamphetamine.

Anaconda Police Chief Tim Barkell tells The Montana Standard that 29-year-old Michelle Yallup of Butte tested positive for meth at the hospital. Hospital staff contacted Child Protective Services and then alerted police early Wednesday after Yallup left with her baby.

Authorities have issued an arrest warrant for Yallup on a charge of endangering the welfare of a child. She is 5 feet, 6 inches tall, brunette and weighs about 120 pounds.

Barkell says Yallup used her sister's name when she checked into the hospital. The vehicle Yallup was believed to be driving was found at her sister's house in Butte.