Generally speaking, it is considered safe to nurse during pregnancy. However, you should always run these questions by your OB GYN doctor
- which you might be able to do over the phone quickly if you can't get in to see them for a while. I say this because the one major risk of breastfeeding is that it might cause some uterine contractions. Although this is unlikely to be much of an issue early in pregnancy, it could be a problem if you have a history of premature uterine contractions or labor. Your doctor will be able to tell you if it is safe for you to nurse.
There are a few other minor issues as well. First, the flavor and consistency of the breast milk does change gradually during pregnancy, and you might find that your young child is put off by this. This doesn't mean that there is anything wrong with your breast milk, per se, but it might influence your child's willingness to continue breastfeeding. Furthermore, many women find that the amount of milk they produce decreases dramatically as the pregnancy goes on.
Call your doctor to make sure that there are no particular issues that would prevent you from breastfeeding, and congratulations on this pregnancy!