BeSha’ah tovah!
There are different approaches to women with confirmed pregnancies fasting on Tzom Gedaliah. Common practice is for pregnant women not to fast. For more details, please see our article, Pregnancy and the Four Fasts.
The halachot of fasting on Yom Kippur are much more serious. We recommend reading our article on Pregnancy and Yom Kippur, consulting with your physician, and then discussing any concerns with a halachic authority.
Ketivah vachatimah tovah!