Having a child and the upfront costs can be high. Delivery/hospitalization costs, immunizations can be cheap if you go polyclinic/Govt and don't stay in A class, stroller, pram, playpen, bedding,clothes, breast pump machine, are all upfront costs. You can get estimate of medical costs from MOH website. You can save on necessary items (pram,etc) if you buy used ones, or borrow from friends/relatives.
Once the child is born, the cost is low. Child eats little. Even diapers and milk is not very expensive.
Until about 18 months old, you will have options for child's education... like play group..all these are options which cost money.
If you plan to have a maid,then cost will be higher each month though. Levy is $200 plus maid's salary between 240 to 320 for inexperienced maids (different nationality).