All your hospital bills for maternity will be claimable via Medisave not cash.
For subsidies, you can only choose ward B2 or ward C. I agree with Anonymous that you'll only be staying in the hospital for a day or 2 for normal delivery or 3 days for c-sect and that is, if there is no complications after delivery. Visitors are allowed but depending on which hospital and only a few numbers can come since it's Covid. You will have to fork out cash if you choose the private ward like A1 or B1 and all your consultations after that will be considered as private too.
During your 1st few consultation, you will be given a piece of paper on roughly how much your hospital stay will be. Keep that to note.