Haha you're not the only one, but unfortunately it will draw scrutiny as their inclination will be to say that he married you to get back into Canada. Sad but true. It doesn't necessarily have to mean an interview though, again, it's all how you present it. The reason for calling for interview would be for you to prove that your relationship naturally progressed to marriage, and was not done to gain entry to Canada. Your job is to prove this up front in your application, so that they won't have anything additional to ask. Sadly, babies don't mean anything to CIC. They have stated quite clearly that "all a baby proves is that two people had sex". If your case looks weak to them, a baby won't help. HOWEVER... if you've got a strong case, having a baby on top of that can only make you stronger. It's all in the presentation
Also YES, you should definitely include a cover letter separate from the forms! It's one of those things that they don't tell you but earns big points. For one, it shows you're super organized, which they interpret as a sign of a genuine relationship (fraudsters won't put in that much effort). Second, it gives you the opportunity to present your case the way you want them to see it, to guide them through all your evidence and frame your story for them. Think of it as the opening statement in a trial. It's also the opportunity to point out any potential red flags and address them head on, rather than leaving the VO to come to his/her own twisted conclusion. Finally, it allows you to walk them through how you organized your application, so they can find everything quickly, as likely your package will include things that are not on the CIC checklist.
Another suggestion... while it usually isn't worth the $2000-$3000 an immigration consultant will charge to represent you, it is totally worth the $200 or so they'll charge you to look over your case. Most consultants offer this service. You simply bring in your completed package and they will look over it through the eyes of a VO and give you any feedback on how to make it better. It's soooo worth a couple hundred bucks. If you can do this, I'd strongly recommend it!
Oh yeah... I forgot lol. Yeah, you're on the last leg brother, don't worry