Anyone have any good books/resources about strength training while pregnant?

I've been lifting heavy/working out consistently for the past 5 years or so and really want to keep up a routine as long as I can during this pregnancy. Not crossfit, but similar moves with 2-3 full body workouts/week. I've already scaled down a bit, but I'm still pressing 50+ and squatting/dl-ing 90+. I'm sure I'll need to scale down even more once I'm further along (5w5d today).

I just got an information packet from my obgyn, and one of the first things on there is "no lifting over 20lbs repeatedly". I'll ask the doctor about it at my first appointment, but I'm worried she's going to tell me to stop with the heavy weights and switch over to 2lb dumbbells.

So I'd like to have some research/information to back me up, b/c I really want to keep lifting but I would also like my doctor's blessing. Any suggestions or advice?