A nanny put poppy straw in the soup of a young mother so her breast milk would contain morphine and make her newborn baby sleep longer, Qianjiang Evening News reported yesterday.

Police in Taizhou City of east China's Zhejiang Province, said the nanny, surnamed Wu, is in custody pending their investigation after an online post revealed the young mother found poppy stems in her fish soup. Wu said it was just for seasoning and swallowed the stems.

The young mother remained skeptical because she didn't remember seeing that seasoning in the house before.

Days later, a family member found a package of poppy straw in Wu's bag.

They immediately alerted the police.

Wu confessed poppy straw fed through breast milk can make babies sleep longer, thus making her work easier.

Zhou Peng, a pharmacist at Taizhou Hospital, said poppy straw contains morphine, which pregnant women and breast feeding mothers should avoid.

He said morphine can lead to health problems in infants.