A Bronx infant who suffered a fractured skull when she fell out of a second-floor window was accidentally dropped by her 9-year-old brother, sources told The Post.

Jakeina Dubose was in stable condition at Jacobi Hospital after the fall at about 8 p.m. Tuesday from her home at the Edenwald Houses on East 226th Drive.

Investigators initially believed the girl was thrown out of the window intentionally, but after interviews with her brother, they believe the incident was an accident, the sources said.

The siblings were in the apartment with two of their uncles and an uncle’s girlfriend, but the 9-year-old had been put in charge of baby-sitting the 3-month-old, a law-enforcement source said.

The brother, whose name is being withheld because of his age, became very frustrated with Jakeina’s crying, and held her near the window in hopes his mom would hear the screams and come back home, the source said.

When that didn’t work, he took the still-screaming baby and held her out of a different window to attract his mother’s attention — and the squirming infant wriggled out of his hands, according to the source.

The incident is still under investigation, but no charges are expected to be filed against the boy.

The other six children — three of each gender — of the baby’s mother, Takeya Dubose, were removed from her home yesterday by the Administration for Children’s Services.

The mom has a history with the agency. It had received several reports that Dubose is often drunk and was intoxicated when Jakeina went out of the window, an agency source told The Post.

Child-protective service agents have been called to Dubose’s home twice before, sources said.