It follows the death of Malak Thawley, who died following routine surgery for an ectopic pregnancy in May 2016
Out of hours standards at the National Maternity Hospital (NMH) will be examined by the health watchdog as part of a review ordered by the Health Minister.
It follows the death of Malak Thawley – who died following routine surgery for an ectopic pregnancy in May 2016.
Simon Harris says he has grounds to believe that patient safety is at risk in relation to the provision of surgery outside of core working hours.
Minister Harris is also concerned about the readiness of the hospital to respond to major emergencies.
The Health Watchdog is to begin investigations immediately.
The terms of reference, which have been published on the HIQA website, include: "To investigate, determine and evaluate the appropriateness of measures employed at the National Maternity Hospital to manage risk and ensure safety in the conduct of obstetric or gynecological surgery outside of core working hours."
It will include a particular focus on "the presence of required senior medical clinical decision makers during the conduct of surgical procedures outside of core working hours".
The hospital has previously apologised to the husband of Malak Thawley, and last month settled a lawsuit taken by Alan Thawley - after what his lawyers described as a cascade of negligence.
The National Maternity Hospital has sought judicial review to prevent a HIQA inquiry taking place, and the High Court will rule on that next month.