My wife is in her fifth month of pregnancy. Her doctor (daati leumi) does not encourage fasting. Additionally, I saw that Dayan Fisher and R’ Shlomo Zalman were very lenient. Can she rely on this?
According to most poskim, including R’ Shlomo Zalman (see Nishmas Avrohom 554-1, Halichos Shlomo 16-2) there isn’t a blanket heter for pregnant women not to fast. If however she is showing signs of dehydration, i.e. dizziness, severe headache, then she doesn’t have to fast. In general determining if she has to fast or not, should be discussed personally with your local Rov. Needless to say that she should make sure to stay indoors, in an airconditioned room, and make sure to drink a lot on the days before the fast.
May we all be zoche to see the rebuilding of the Bais Hamikdash soon.