Hi,
Welcome to the ehealthforum and I am glad to help you out. First possibility that needs to be ruled out is any GERD( gastroesophageal reflux disease) which is quite common in pregnancy. Try raising the head of your bed about four inches with blocks. It also might help to avoid eating or drinking for two hours before you lie down. To help control the stomach acid, one should not drink alcohol or drinks with caffeine in them, or eat chocolate or spicy or greasy foods .
Take some OTC antacid like Mylanta. You can also take zantac(ranitidine)or prilosec(omeprazole).These will help. Also keep your fluid electrolyte balance optimum by drinking lots of fluids. If the symptoms persist then please get it evaluated from a gastroenterologist. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.