Being pregnant increases you estrogen level. This can affect your gall bladder. You can feel pain almost in your back or sort of directly behind your ribs.
I suffered for years ending told I had indigestion. Obviously fatty foods makes it flare up. Then being pregnant tipped it over the edge.

"Women are more likely to develop gallstones than men. Extra estrogen can increase cholesterol levels in bile and decrease gallbladder contractions, which may cause gallstones to form. Women may have extra estrogen due to pregnancy, hormone replacement therapy, or birth control pills."