Having read that again I think the chances of you getting through US immigration with your pregnant US citizen wife (and your personal belongings) are basically nil, I can't see how any CBP agent would believe you have non-immigrant intent. Visitor status requires an abode abroad. Well at that point you've left your abode in
China and you no longer have one in Canada either.
Can't really think of a good solution for this one. She returns to the US, you return to Canada and establish residential ties, and she sponsors you for permanent residency. Hopefully by the time the baby reaches the due date you'll be able to convince CBP you're visiting, not immigrating, so you can at least go to the hospital with her.
Or there's the dicey-and-not-recommended route of visiting and then applying for AOS, but even that would require you to spend some time in Canada, because at the moment you don't even qualify simply as a visitor as you have no abode abroad.
But this is all covered on
www.visajourney.comLike Reba said, don't lie. Not worth the risk. If you get banned from visiting it's an inconvenience. If you get banned from seeing your wife and child, big problem. Better to be patient.
Steve.