"If your child was born in Canada or if one of its parents is a Canadian citizen, the child is therefore a Canadian citizen. If that is the case, you do not need to add the child to your application, no medical examination or fee is required. You must, however, send us a copy of his or her birth certificate. The child must have a Canadian passport to enter Canada.
If this is not the case, you must add the child to your application by sending us a copy of the birth certificate along with 4 identity photos. Your child will have to undergo a medical examination. If the child is accompanying you to Canada, you will also have to pay the required fees, submit a copy of the child's passport and obtain a Certificat de sélection du Québec (CSQ) in his or her name if your province of destination is Quebec."
This is from the canadian website. You just need to send the birth certificate.
Also this thread is useful for you to read:
http://www.canadavisa.com/canada-immigration-discussion-board/child-born-to-a-canadian-citizen-outside-canada-t61657.0.html