A new mother in Kyoto who claims she injected amphetamine to ease her labor pains is now under arrest after her newborn tested positive for the illegal drug, police said on Thursday.

"I injected amphetamine on the day I gave birth to my baby because I couldn't stand the labor pains," the unemployed woman, 26-year-old Kana Shimizu, was quoted as saying.

Born in critical condition at a Kyoto hospital on Sept. 24, the baby boy has recovered and is now in an orphanage for newborns, an officer at Kyoto's Higashiyama police station said. The transfer to the orphanage is apparently a temporary arrangement and because the baby's father has not stepped forward to care for him.

The hospital called police on Sept. 28, once the results of a urine test became known.

Shimizu disappeared from the hospital the same day, but returned to the hospital on Oct. 20 to check on her baby, the officer said.

Upon her arrest that day she was found to be carrying 2.5 grams of amphetamine and 0.2 gram of cannabis. She was quoted as saying, "I possessed them for the purpose of selling them."

The woman has already been indicted.