Q. 1. What is the Catholic Church teaching regarding fasting when one is pregnant?
A. 1. The Catholic Church does not have a specific teaching regarding fasting when one is pregnant.
I suspect that your question is related to: Canon Law # 919 §1 where it states "Whoever is to receive the blessed Eucharist is to abstain for at least one hour before holy communion from all food and drink, with the sole exception of water and medicine."
Canon Law # 919 §3 would answer your question. It states: "The elderly and those who are suffering from some illness, as well as those who care for them, may receive the blessed Eucharist even if within the preceding hour they have consumed something."
"Those suffering from some illness" would certainly include women who would suddenly have a need to eat or drink something during their pregnancy.