All payments are to be paid promptly after each check up. Subsequently you can use the Health Buddy Apps and you make the payment through it. If I correctly remember you can amend amount. However, there are some check up like vaccine only you can pay through medisave.
After birth, only then you can claim Pre Natal check up expenses. This will be process and thereafter return by cheque together with whatever necessary.
Should let say, you have difficulty to make payment or having issue with financial, you may approach MSW Social Worker) opp MotherCare to seek assistance. They will review the application and get back to you. But, this will only apply to Class C/B2 (6 bedder).