In a newly-published report, the SPSO said the health board had failed to provide adequate advice, care and treatment before and during the baby's birth in October 2009.
Meanwhile, a patient who was told she was dying and given the last rites, but who went on to make a full recovery, has had her complaint upheld by the SPSO.
The SPSO went on to criticise NHS Western Isles for saying that a review had been carried out, when the findings of this review had not been passed to all staff.