i think it's really wise of you to be thinking about the safety aspect of the move for your pregnancy. i have moved while pregnant (3 months) and i had a 1 yr 3 month old to care for as well. that was HARD and probably not the best thing for the pregnancy, but i also had other complications which made it worse.
but do you have other kids? and do you have any reason to believe you will have a difficult pregnancy?these would be the 2 big reasons for me to stay put in the US where I have family/friends. i don't think moving to your new home in hong kong would be vastly different from moving to a new home in the US (i have moved while 7 months prego in NYC!), in fact in some ways it could be much easier because the level of service here is so much better-- for one, you can have full time help for not a lot of money. (meaning someone to unpack your stuff, run errands, cook, clean, etc.) also, it is possible to rent a fully furnished flat here or stay in a serviced apartment (maid service, fully furnished) until you are able to make your own home.
the quality of care here is really excellent so you need not worry about that.
i've heard of many people moving overseas while very prego. i think the key is to be mindful that you need to take it easy, set reasonable expectations for what you can accomplish, set prioroties, and make sure your husband appreciates your/your baby's needs! good luck.