Canada is one of the safest country in the world for women as well as kids so as far as only safety is concerned I don't think there should be any worry.
I don't know where you originally are from, but if you have exposure to western culture and rules it will be much better for you. If you are from India or Pakistan, you may need lot of adjustment.
There are lot of rules to be followed for children and the basic one will be to not leave them alone, if all of them are under 13(I am not sure about the age). So if you plan to get a job, and all your kids are under 13, you'll need babysitter or similiar services, which you may not be able to afford in the initial stages.
Secondly having kids with you initially will restrict you movement i.e. you may not be able to move to a new location for a better job because of kids. In my opinion both of you(husband and wife) and if not possible only you, move initially for maybe 3 to 4 months, check out job market and location for settling down.
Rest upto you...
Best of luck!!!
http://www.chatham-kent.ca/default.htm
http://www.hc-sc.gc.ca/hl-vs/child-enfant/parent/index-eng.php
