Your second prenatal visit typically falls around nine weeks (although it may be as late as twelve). In addition to assessing your vitals, your OB may also check the growth of your uterus and use a Doppler (an ultrasound device) to listen for the baby's heartbeat. You might also get an ultrasound around this time to determine the age of the fetus. Determining the sex comes later, usually around 20 weeks.
This would be a good time to ask about what level of exercise is OK for you. Also consider asking your OB about foods to avoid. Many doctors suggest staying away from fish high in mercury, such as tuna, as well as deli meats (which can harbor bacteria that cause a disease called listeriosis).
If your prenatal vitamin -- which should contain folic acid -- is making you sick, there are other options. Try taking it with food or at different times of the day. Your OB can also suggest vitamins in forms that might be easier to keep down, such as a chewable or liquid.
Now that your first trimester is winding down, you may want to think about when you'd like to tell your boss about your pregnancy (if you're working). Many women wait until they pass the 12-week mark, but if you're experiencing severe nausea or other obvious symptoms, you may want to share the news sooner.