He has written to Betsi Cadwaladr University Health Board raising concerns over the move.
Under the changes women needing a consultant will have to go to Ysbyty Gwynedd or Wrexham Maelor hospitals.
Mr Drakeford has asked for "assurances" on behalf of expectant mothers.
He wants a "definitive timescale" on when the service will be returned to the hospital.
In the letter, addressed to the health board, Mr Drakeford said: "It's very important that patients and their families are provided with clear in formation on this very important matter, without any room for ambiguity."
The health board welcomed the letter.
Health Minister Mark Drakeford has demanded an independent report into plans to remove doctor-led maternity care at Ysbyty Glan Clwyd in Bodelwyddan.