North Haverhill — A 24-year-old Lebanon woman accused of shaking a baby so hard that the baby suffered an injury to her brain has pleaded guilty to first-degree assault.

Kayla Cassady was sentenced to serve one year in jail, according to court documents.

She also pleaded guilty to possessing a controlled drug, and received a suspended 1½- to three-year sentence. She also must pay fines.

As part of her plea agreement, Cassady was ordered not to work with children in any capacity, the documents state.

Cassady allegedly shook her boyfriend’s then 19-month-old daughter so “severely” that she caused a bleed on her brain that required surgery, according to a police affidavit filed in the case.

The case began in October 2017 after police responded to an apartment on Pine Tree Lane for a report of a young female who was not alert. Cassady initially told police the girl, who she was watching, appeared to suffer an unknown medical problem, but later revealed she shook the child, according to the affidavit.