Like Madhu TK & Kamesh pointed out, you can take a tough stand. However, while doing so, please ensure you don't lose your sleep or peace of mind over the issue.
Regular Updates to Your Husband
First and foremost, please update your husband regularly on what's happening. This will ensure you can go back home daily to actually recoup after the grueling sessions at the office, which you have already begun to experience.
Document Everything
Secondly, as Kamesh suggested, don't give them a chance to point out any shortcomings or lacunae regarding your performance. One way to handle this part (since one never knows how things can be interpreted later) is to put down EVERYTHING in writing - your daily reports, minutes of meetings, etc. Basically, anything you 'feel' can be misinterpreted or misconstrued later to your disadvantage.
Involve HR Informally
Next, if you have a lady in your HR department (since you haven't mentioned how large your company is), take her into confidence. The idea is not to complain or escalate the matter but to ensure (in a worst-case scenario) you don't give HR a chance to say later, "WHY DIDN'T YOU TELL US EARLIER?" Also, check if HR will intervene on your behalf with your manager.
One option that might open up if you involve HR INFORMALLY is this: if they also find the manager adamant, they might shift you to another group or project where you can work more effectively (of course, this depends on your company size too).
Seek Forum Support
If your experience with HR isn't that encouraging, suggest giving your feedback in this forum - I am sure all of us can find ways to handle them too. After all, it takes a thief to catch a thief :-)
Lastly, as I mentioned at the beginning, this is the time for you not to feel stressed. So the sooner you sort out the issue, the better for you... and the unborn child.
Regards,
TS