In general, once you are pregnant, you will not be granted the visa. However, Canada is now considering visa for pregnant women, so be patient, since the news may come out soon probably in a few months. To deliver a baby in Canada, you will be charged from C$1200 to C$2500 per day, depending on the location. So, if you stay in hospital for 3 days, you will have to pay 30,000 rmb. Your son will have Canadian citizenship but you won't. You can take your child back to China, with your child's Canadian passport or a travel permit issued by the Chinese consulate office. Your child cannot sponsor you to migrate to Canada until he turns 19 and meets the sponsorship requirements.