Rennie for me! They taste like chalk but the relief is instant...

Also, try small frequent meals instead of large servings.

It's caused by your growing baby placing pressure on your stomach and forcing open the valve between your stomach and your oesophagus. This valve usually prevents anything from heading up and keeps everything down. Once it is forced open, those lovely gastric juices and digestive acids are free to play where ever they like! Not very pleasant, but very normal.