It is generally safe to consume yeast-containing food during pregnancy, including dishes like Kerala appams. Yeast is a common ingredient used in baking and cooking processes, and when consumed in moderation, it poses no significant risks to pregnant women or their babies. However, it's always advisable to consult with your healthcare provider before making any dietary changes or consuming unfamiliar foods during pregnancy. They can provide personalized guidance based on your specific health condition and needs. Additionally, ensure that the yeast-containing food you consume is prepared hygienically and cooked thoroughly to minimize any potential risks of contamination.