The "correct" method is to get the baby a Canadian passport. Of course, its unlikely you will be stopped just because they didn't have one as long as you have an eTA. IRCC would need to prove the child 'wasn't' Canadian which if just the father travelled for example, wouldn't even come up. So if you really must travel without, an eTA should be good enough.
They key word is proof. It's all very saying it's "fraud" (which I think is a bit far-fetched), but IRCC haven't exactly made it easy for situations like these - they've not thought through all the scenarios which is poor planning on their part. Also, even if one parent was Canadian, it doesn't automatically give the right to citizenship (if for example the parent was adopted from another country at birth, it would mean any children born outside of Canada DON'T get citizenship automatically). The rules are not black and white.
Having said this, if you get the baby both passports - it saves any hassle with travelling, although it is a hassle to get in the first place of course amongst everything else you need to deal for a new born....
They key word is proof. It's all very saying it's "fraud" (which I think is a bit far-fetched), but IRCC haven't exactly made it easy for situations like these - they've not thought through all the scenarios which is poor planning on their part. Also, even if one parent was Canadian, it doesn't automatically give the right to citizenship (if for example the parent was adopted from another country at birth, it would mean any children born outside of Canada DON'T get citizenship automatically). The rules are not black and white.
Having said this, if you get the baby both passports - it saves any hassle with travelling, although it is a hassle to get in the first place of course amongst everything else you need to deal for a new born....