had a similar experience. i notified cic via email. they instructed me to complete a new form IMM 0008: APPLICATION FOR PERMANENT RESIDENCE IN CANADA 'including all dependent children'. they requested for long form birth certificate and photographs and fees. this was CIC london by the way. i will advise you to do this ASAP otherwise they are going to send you medical forms excluding the new baby as happened to me. i guess if you have more than 2 children then they might send you a separate form as the forms have space for only 2 children. goodluck.
You need to send 4 Canadian immigration photos of you child along with :
*$150 processing fee for your child
*your child’s birth certificate
*copy of your child’s valid passport (if available at the time, If not available it can be sent later when they eventually request the originals for everyone when it is time to issue PR visas.
*3 recent photographs of your child
*updated IMM0008 Generic for yourself and updated IMM5406 “Additional Family Information” form for yourself and your spouse.
a “Certificat de Sélection du Québec” for your child ( in his or her name), if you wish to immigrate to the province of Québec (http://www.micc.gouv.qc.ca/fr/index.asp)