The mode of delivery depends on a lot of factors. The doctor has advised you correctly as we have to wait and see what is the expected baby's weight after you complete term. If the baby is big and if your pelvis is not adequate ( especially if you are short statured), then a normal delivery becomes difficult, and could be harmful for both you and the baby.
If the baby develops any distress during the last months of your pregnancy
, you may have to undergo a c-section for the sake of your baby's wellbeing.
Even if you get adequate pains, but if your cervix
doesn't dilate properly (i mean if your labour doesn't progress properly) you may have to have a c-section. If the baby develops distress during your labour, and if its not possible to deliver you quickly, c-section maybe necessary.
If the baby doesn't come down properly (example if the baby's butt is down instead of the head, if the head isn't in the right position-called malpresentations and malpositions), normal delivery maybe difficult/impossible. The position of the baby becomes fixed only in the ninth month.
If you develop any complications like severe Hypertension
etc, you may need a c-section for the sake of your wellbeing.
Hence there are a lot of factors to consider. I have just mentioned a few common things for your knowledge. Your baby and your wellbeing is more important than how you deliver. And your gynecologist will explain all these when the time comes so that you can take the appropriate decision that time. Till then focus on having a healthy baby and being a healthy mother.