It's a little difficult to tell from the picture, but it could be psoriasis or eczema.
Neither one will affect the baby, so no worries there...however, some creams and other meds may not be used during pregnancy.
You will need to talk to your doctor or ob/gyn to determine which medications/creams will be safe to use.
Have you used any new shampoos, conditioners, coloring, perm solution, or any soaps lately? These can all cause irritation such as in the picture.
Pregnant skin is sensitive skin.