I have never had acid reflux until pregnancy. It is not fun. It is fact, quite gross. There is acid sitting in my throat and it is horrible. Why does it happen? Because of my mega uterus which is squashing my stomach and sending stomach contents back up the pipe (YUMMY). Also, because of my mega prego hormones which are relaxing things that are normally tight (in this case, oesophageal sphincter). I am supposed to drink lots of water, but apparently, that can also exacerbate things by filling up the tummy.
Conclusion: just screwed. Deal with it.