(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."

Read More