Hi J.: I didn't see this mentioned previously even though you got a number of responses already...
It could be PUPPP: pruritic urticarial papules and plaques of pregnancy (PUPPP) or polymorphic eruption of pregnancy... or prurigo of pregnancy. On a rarer level, I have a friend who was so itchy during her pregnancy... Her doctor kept dismissing her complaints. Turns out her kidneys (maybe it was her liver) wasn't processing all the wastes as efficiently and the build up was making her skin itch... So you definitely want to mention this to your OB.
Hope you feel better!
Below are some tips from the Baby Center:
Is it normal to feel itchy during pregnancy?
It's not uncommon to feel itchy, particularly around your growing belly and breasts as your skin stretches to accommodate them. Hormonal changes may also be partly to blame.
Some pregnant women find that their palms and the soles of their feet get red and sometimes itchy. This common condition may be caused by an increase in estrogen. It usually disappears right after delivery.
You may also find that things that normally make you itchy — dry skin, eczema, food allergies — make you even itchier when you're pregnant. Finally, there are certain conditions that occur during pregnancy that may cause you to feel itchy.
How can I get relief from the itching?
Avoid hot showers and baths, which can dry out your skin and make the itching worse. Use mild soap and be sure to rinse it off well and towel off lightly. Then slather on an unscented moisturizer — some scents can cause irritation.
Try an occasional warm oatmeal bath. (You can buy oatmeal bath preparations in drugstores.) Wear loose cotton clothing and avoid going out in the heat of the day, since heat can intensify the itching.