The deaths are examined in a review of the safety of neonatal services at Caithness General Hospital published recently by NHS Highland.
An external independent inquiry featured in the report considered the two stillbirths and three neonatal deaths from 2010 to 2015 and concluded that at least two of the deaths were “potentially avoidable”.
“Sub-optimal care” and “avoidable factors” were recorded in all five of the perinatal deaths analysed.
It comes a week after the Scottish Government ordered a review following six so-called “unnecessary” deaths of babies at Crosshouse Hospital in Kilmarnock, East Ayrshire, since 2008.
Scottish Labour has called on ministers to announce a national review of staffing and workforce issues across all maternity units.
The comprehensive 116-page report into maternal and neonatal services at Caithness General Hospital will be discussed tomorrow at a meeting of the NHS Highland board.
It recommends that Caithness Maternity Unit should operate as a midwife-led Community Maternity Unit (CMU), on the grounds of safety, while cases with a risk of complications should go to Raigmore Hospital in Inverness.
The review was prompted by the potentially avoidable death of a newborn baby at the hospital in September last year.
NHS Highland’s medical director Dr Roderick Harvey, who ordered the review, said: “Families do rightly put their faith in the health service and the fact that infants died possibly as a result of sub-optimal care is unacceptable and I apologise unreservedly for these past failings.
“That is why I commissioned the current review and I would wish to assure you that the families have been uppermost in our minds when conducting the review.
“Having identified real safety concerns in my view we must move swiftly to address these concerns and that is the basis of my recommendations.”
There have been no legal claims over the deaths, the health board confirmed.
No members of staff have been disciplined as a result of the five deaths because “any identified deficiencies did not reflect on individual clinicians, but rather the system that they work in”.
Last week, Health Secretary Shona Robison instructed Healthcare Improvement Scotland to carry out a review into certain cases in Ayrshire and Arran “to inform me whether the correct procedures and processes were properly followed” in these instances.