A Bronx infant died early Saturday after her mother took her to bed with two siblings, police said.

The baby’s 31-year-old mom told investigators that 17-day-old Leah Trent was crying Friday night, so she brought the girl and her two sisters, ages 6 and 13, into the same bed.

The family fell asleep, and the mother awoke in the morning, to the crying of the older girls. She realized her infant wasn’t breathing, sources said, and immediately dialed 911.

The mom was being questioned, but had not been charged with a crime. The medical examiner will determine the cause of death.