I have a friend who had a child birth in Buffalo, NY. The deliver charge was $5000 USD for the operation and 4 day hospital stay.
Now here in Canada, assume there are 6-10 OB visits (120 each) and 2-3 Ultrasound (100 each) and , you are looking at ~$1500 Canadian leading to the labour. Now 4 days hospital stay is $400-600 and I dont know who much they charge for the delivery and medicines that used in delivery. Vaccine shots I assume will be free to your kid, since he/she is a "born Canadian" and covered under OHIP (there is 12-15month period to complete all the shots)
But these are all counting on no complication for the mon and bb before and after the labor, which could sway the total 200% - 1000%. Buttom line, you really should get some kinda insurance. If you are at school, your health insurance should cover that. But for all other reasons, note: NOT all health insurance for visitor cover child birth. (i.e. they are not suckers
)
Also even though your kid will be a born Canadian, be careful, it will not make a difference to your immigration status until he/she is 18.
All in all, it is risky. But you got to do what you have to do. You are likely have to spend alot if you were in China as well, if you have no insurance and guan-xi. (I have classmate had child in China and spend $3000 RMB in red pockets for the Doctors on top of all the regular hospital fee ~$1500)
Talk to some local support groups that have sections to non-canadian visitor!!
http://www.parentresource.on.ca/results.asp?searchtype=3&toc=540&heading=Parent Support Groups
http://www.mothercraft.com
http://www.immigrantwomenservices.com
Jewish Family Services 722-2225 (it is open to all, especially new-comer)
All the best!