I just got back from my appointment with the maternal-fetal medicine doctor, Dr. Lantz. In summary, everyone is doing fine. I had a nuchal translucency screen (a screening test to check for possibility of downs syndrome) today and met with the doctor. Dr. Lantz came in to take a look, and he said that one of the characteristics of downs babies is that you can't see their noses at this stage. We then looked at both babies, and we could clearly see a nose on each. Also, he said that the fluid on the back of the necks measured 1.8mm and 2.1mm. Anything less than 3mm is a good sign. The babies both measure between 2 and 2 1/2 inches from head to butt.
The ultrasound identified all of the major anatomic landmarks: arms, legs, head & face, a stomach, and a bladder on both babies. I heard the heartbeats for the first time, 159 and 161, which are both very good numbers. The ultrasound tech also looked at both of my enlarged ovaries, and verified the placement of both placentas: one is anterior and one is posterior (good--we didn't want either of them to cover my cervix). Everything checked out okay. She asked me if I wanted to know the sexes, so she told me with 80% confidence that baby B is a boy! They were both moving around a lot, doing flips, turns, and moving their arms and legs. Because of the continuous movement from baby A, she was unable to determine its sex. Dr. Lantz verified this information, stating that it was pretty difficult to tell, but he also thought baby B was a boy. Hopefully, we'll get confirmation of this and find out the sex of baby A at my 18 week ultrasound.
I am finished with Dr. Lantz's office unless something drastic happens. From now, on, my pregnancy will be treated similar to a singleton, only with more frequent ultrasounds.

Baby A at 12 weeks, 1 day

Baby B at 12 weeks, 1 day

This is a picture of Baby A's face. The ultrasound tech said the baby was looking right at us, but I can't see it.