I was extremely scared and avoided mangoes in my first trimester, but my doctor said a small glass of fresh juice is fine later on. If you have any history of complications, do check with your doctor first.
My mother used to make fresh aamras for me almost every day during the season. Just ensure the mangoes are washed properly before juicing, homemade is always best.
I couldn't digest anything, but chilled homemade mango juice was the only thing that stayed down. Just make it fresh at home and avoid canned ones with chemicals.
I drank fresh mango juice almost every day during my third trimester in summer! Just make sure not to add extra sugar, and keep the glass size moderate.