CNN  — 

An Ohio mother was sentenced to two consecutive life sentences plus seven years Tuesday after pleading guilty to smothering her three young sons to death over a 13-month period, prosecutors said.

Brittany Pilkington, 27, pleaded guilty to two counts of murder and one count of involuntary manslaughter for causing the deaths of her three sons between July 2014 and August 2015, according to Ohio Attorney General Dave Yost and Logan County Prosecutor Eric Stewart.

The boys – Niall, Gavin and Noah – died in July 2014, April 2015 and August 2015, respectively, the prosecutors said in a statement.

The court imposed two consecutive life sentences for the murders and an additional seven years in prison for the involuntary manslaughter charge, the statement said.

“A guilty plea cannot undo the heartless acts this woman committed against defenseless children,” Yost said. “She does not deserve to be called mom. But locking her up will at least guarantee she won’t be able to repeat this evil.”

Stewart said the indictment initially called for the death penalty but a state expert advised the penalty “was not appropriate in this case due to the mental defects of the defendant.”

“Everyone involved in the case, including investigators, family members of the victims, and this office believes that the two consecutive life sentences is a proper resolution which will bring justice and closure to this tragic case and protect the community from the defendant,” Steward said in the statement.

Defense attorney Kort Gatterdam said Pilkington suffered brain damage from lead ingestion as an infant, CNN affiliate WDTN reported. A medical scan confirmed the damage, which led to developmental delays as well as emotional and anxiety issues.

She also suffered sexual abuse by her husband Joseph and the father of her four children, Gatterdam said. In 2016, he pleaded guilty to a misdemeanor sex charge stemming from his relationship with Brittany before their marriage.

In August 2015, emergency responders were unable to resuscitate Pilkington’s 3-month-old baby Noah, when he stopped breathing – less than a week after a court returned him to his mother, authorities said.

The same had happened with her 4-year-old son Gavin when he died in April 2015, and 3-month-old son Niall when he died in July 2014, prosecutors said. Pilkington confessed when confronted by investigators.

Prosecutor William Goslee said at the time that Noah and his sister had been returned to their mother just six days before his death.

Pilkington had called 911 early one morning to say Noah couldn’t breathe. She initially said she believed genetics played a role in the deaths of the boys but she later admitted to suffocating them to death.

She will be eligible for parole in 37 years, WDTN reported.

CNN’s Matthew Stucker contributed to this report.