All, thanks for the great advice. Sorry I hadn't been back on this forum for awhile because I ended up going to my doctor and while I did not ask for bed rest explicitly, I told her my situation. She thankfully said the baby looked fine, but that continuing conditions like the ones I was being put through would eventually be bad. So I got a note like starbucks2 which recommended a 40 hour week. I gave it to my HR person who then contacted my partners (I am an IPO lawyer) and they have been good about my schedule since.
As to whether limiting my hours in this way means I'm not performing, well, I think it is certainly true that all nighters and long hours are part of my job. If there are coworkers who resent me right now, so be it - I have more important concerns, and I do try to be efficient in the time I am at work. Quite simply, I busted my ass for this law firm for over 4 years now, survived the layoffs, put in countless hours and made them a lot of money, so I think they can deal with me giving them a 'normal' workday for a few months.
One interesting thing that happened was that when I first gave my note to the HR lady, she suggested I voluntarily go on part-time program and reduce my salary and benefits. I was surprised and said I had been reading up on US laws (my law firm is CA based and I originated in a CA office before being transferred to their HK office) and pregnancy is treated as a 'temporary disability' in which if the employee needs to take time off or limit hours temporarily, the government will compensate for the difference. The employee should not suffer a reduction in salary or benefits. That is exactly what happened to my coworker in one of the US offices when she had to take 2 full months of bedrest. I was only requesting a normal working day. I think in HK the rules are different and once I said that seemed discriminatory to me, she backed off and then asked the head of HR in the US who confirmed that I could just limit my hours to 8 a day without having a reduction in my salary. Of course, I have still gone above those hours on many days, but try to at least work from home when it gets past 8 hours.
On a separate note, I really don't see how anyone has a normal working schedule and raises children in HK in my industry with the kind of work ethic/expectations they have here. I know where I was from before, there are plenty of moms working full-time for slightly less pay but normal working hours at companies. HK is just special I suppose.