A 19-year-old Yonkers woman violently shook her 1-month-old son, leaving the baby hospitalized with bleeding on his brain and a broken rib, authorities said.

Brandy Niemiec, of Glenwood Avenue, was charged Wednesday by police with two counts of reckless assault of a child, a felony that carries a maximum penalty of seven years in prison.

The baby boy, whose name was not released, was born July 14, authorities said. Yonkers police Det. Dean Politopoulos said that on Aug. 23 between 9 and 10 p.m., Niemiec shook the 5-week-old baby while putting him down to go to sleep.

"During this conduct the defendant stated she heard cracking come from the child's body," Politopoulos said in a felony complaint filed against Niemiec.

Niemiec's family did not return calls seeking comment. A lawyer for her could not be located.

She was awaiting arraignment later Thursday in Yonkers City Court.

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The second incident occurred last Saturday, police said. Again, Niemiec assaulted the baby as she was placing him down to sleep before 11 p.m., police said. As in the first incident, she grabbed the baby around his torso and violently shook him, police said.

The baby suffered subdural bleeding, bleeding in his eyes and a broken rib, according to the police.