I coincidentally just got this in a pregnancy e-newsletter today, hope it helps!
Why is my skin so itchy?
During pregnancy, your skin is stretching to accommodate your growing baby and any other weight gain, and your fluid needs are growing, so it's harder to stay adequately hydrated. That combination is a recipe for itch, says Margaret Pfeifer, an obstetrician and gynecologist at the Mayo Clinic in Minnesota. Many of her patients complain of itching on their abdomen during the second and third trimesters. If your belly is itchy and your skin is dry, use lots of unscented moisturizer, drink plenty of water, and avoid hot showers and baths. Call your caregiver if you have intense all-over itchiness because that can signal a serious condition called cholestasis of pregnancy. And let her know if you develop any kind of rash so she can evaluate it and recommend appropriate treatment or refer you to a dermatologist.