My eczema, which has been severe at times, is provoked by the nightshade family (potatoes, tomatoes, eggplant, pepper, tobacco) and wheat and milk.
My daughter has severe eczema, and a delayed food allergy panel (blood test) with US Biotek revealed a number of foods that she's reponding to in a delayed fashion. We removed those foods from her diet (wheat, gluten, milk, casein, soy, pineapple, sunflower and a few nuts) and her eczema dramatically improved. The doctor is just amazed.
Whatever foods she craves are probably top eczema contributors.
Suggest that she avoid the top 8 or ten allergens for two weeks (wheat, milk, nuts, etc) and see if t here's a differencein her skin.
Cortisone suppresses the body's natural reaction to an allergen, it doesn't "cure" the allergy. Suppression is not good.
Vaseline and many products come from petroleum, a toxin. The skin is the largest organ, and you don't want to use gasoline (vaseline) or petroleum products, esp during pregnancy.
Finding the offending food and removing it from the diet would be a better option.
Sometimes, digestive enzymes can help an individual digest food better and not react so strongly on the skin. I think they're safe during pregnancy (they're not a drug) but she should clear anything like that w/ her doctor. I am not a doctor and this is not medical advice.