Thirteen Massachusetts children died of abuse and neglect at the hands of their caretakers in 2016, according to newly released data by the state Department of Children of Families.

That’s three more deaths compared to the year before, but still a significant drop in child fatalities since 2013 when 39 child fatalities in the state were linked to abuse and neglect. Four of the 13 children who died last year had been at some time under the watch of state social workers, state records show.

State officials said child fatality data can vary from year to year. But the relatively low number of deaths follows efforts by Gov. Charlie Baker to improve the state agency tasked with helping troubled families. The move followed public outcry over several high profile fatalities, including Jeremiah Oliver, the Fitchburg toddler who disappeared and was later found dead by a highway in 2014. There was also Bella Bond, the 2-year-old child found dead in a garbage bag on Deer Island in 2015, who had twice been under supervision of state social workers.

DCF spokesperson Andrea Grossman said “every child fatality is a tragedy” and each death is scrutinized by state officials as the agency implements system-wide reform efforts. “DCF is committed to making meaningful and sustainable changes that promote the best possible outcomes for children,” she said.

Reforms include lowering social workers caseloads, hiring a full-time medical director and increasing the agency’s budget, which increased from $759 million in fiscal year 2013 to $976.3 million in fiscal year 2018.

State officials released the list of 13 children but identified them only by their first and last initials, citing the need to protect the privacy of family members. The New England Center for Investigative Reporting has been tracking child maltreatment deathssince 2009.

However, some names were identifiable by the circumstances of their deaths. Among them was Kenai Whyte, a 3-year-old Roxbury boy who allegedly was beaten to death by his stepmother Marie Buie, three years after being brought to the attention of state social workers. Buie was indicted for second degree murder in April of 2016 and pleaded not guilty. The case is pending.

DCF documents showed Whyte was first flagged by social workers in May of 2013 following substantiated allegations related to “poor parental supervision” and in 2014 for alleged domestic violence.

Most children who died in 2016 had no history of state intervention. They include 1-year-old Noah Larson who suffered injuries while being cared for by a babysitter in Woburn. In May, the death was ruled a homicide by the Office of the Medical Examiner, although no charges have been filed.

DCF determined that Larson’s death was linked to a “supported allegation of abuse” after he “presented with multiple physical injuries,” data showed. The Office of the Middlesex District Attorney’s office says an investigation into what happened to Larson is “active and ongoing.”

Five of the deaths were linked to what state regulators call “unsafe sleeping,’’ usually referring to children who are put to sleep on their stomachs, wrapped in heavy blankets or sleeping with their parents in a bed or on a couch.

Sudden unexpected infant deaths is the leading cause of deaths of children between the first month and first year of life, according to the state Office of the Child Advocate. Substance abuse has been linked to some of the sleep deaths, DCF said.

The number of child maltreatment deaths have dropped amidst a growth in concerned calls to state child welfare hotlines and an increase in the number of children pulled from homes, DCF records show. On Dec. 31, 2016, for example, 9,442 children were living in out-of-home placements compared to 7,698 on the same day in 2013, according to DCF data.

Facing a shortage of foster parents, the state this year launched a foster parent recruitment campaign and opened 143 new foster homes with parents who completed 30 hours of training.

Peter MacKinnon, president of the SEIU Local 509 that represents Massachusetts human service workers and educators, said more needs to be done to help troubled children after they’ve been pulled from their homes. “There is a stress on the foster care system,” he said.