BeSha’ah tovah!
Whether a pregnant woman is exempt from fasting on a delayed Tisha B’Av is a matter of halachic debate. There is further debate regarding the halachic status of the first three months of pregnancy.
In general, when a pregnant woman does not feel well, there are grounds for her to break the fast of Tisha B’Av in consultation with a rav. We suggest beginning as though you will fast (including entering the fast hydrated and making arrangements to have a restful day) and seeing how you feel. In this case, given that Tisha B’Av is postponed from Shabbat to Sunday, you may break the fast if you begin to feel uncomfortable, without need for additional consultation. After breaking the fast on Tisha B’Av, one may eat freely. Havdalah should be recited before eating.
Please contact your physician in advance of the fast to check if there is additional or special concern, in which case your should get back to us or a local halachic authority.