Pregnancy involves a lot of changes to the body, weight gain, and the fact that there is a baby which needs constant nutrition means that there are several effects of fasting during pregnancy. Some of them are short-term effects and would subside with time whereas others may have implications for the long term.
If you have endometriosis, it may be more difficult for you to conceive. Endometriosis can affect fertility in a number of ways. Most obviously, as the disease progresses and pelvic damage increases to organs such as the Fallopian tubes through distortion or adhesions, the passage of sperm and eggs through the pelvis will be increasingly impaired.