Foster care services in the Highlands are dealing with a "marked increase" in babies from drug-abusing families.
A Highland Council report said it was also accommodating more "out of control" primary-aged boys and older children who had been "young carers".
It said the total number of children in care had remained "relatively static", with a slight increase over four years.
However, it said those requiring family placement posed "significant challenges" because of their needs.
The details were contained in a report to Highland Council's joint committee for children and young people.
The local authority has 172 children currently placed with foster carers.
The report's author said: "There has been a shift over the last six years in the age groups requiring foster care, with a marked increase in the number of babies accommodated, most of whom have serious health and developmental needs generally associated with parental substance misuse."
"There has been an increase in the number of older sibling groups, chatacterized by profound neglect with the eldest having been young carers."
She added: "There are also some very angry, out of control primary school aged boys who are out of mainstream school, and do not have a full education timetable. This can present challenges when carers work as well as foster."
The quality of fostering and adoption services at Highland Council were rated as "excellent" by the Care Commission earlier this year.
The commission made no recommendations, or requirements for the council to meet.
Services for vulnerable children in the Highlands were also praised by the HM Inspectorate of Education.
Five of the six areas evaluated by the inspectorate were rated as "very good" and the remaining one as "good".