hi william, you can check this page to gauge the average bill size for Thomson Medical Center.
Hospital Bill Size | Thomson Medical
Room rates and hospital charges etc are standard but it also depends on doctor's fees as well. Some senior doctors charge alot.
You can also see here for the maximum claims under Medisave.
Marriage and Parenthood Schemes | Ministry of Health
For normal delivery maximum is $2550 and C-sect is $4400 so from here you should be able to gauge the cash payment needed.