It is normal -
Our stomach and intestines are also processing food a lot slower, thus contributing to a lot of gas and heartburn. I'm sure these are causing some of the pressure you are experiencing.
Also, the gallbladder is located under the right rib cage. If you develop very severe sharp pains under the right rib cage (especially after eating a fatty meal), you may have gallstones (much more common in pregnant women).
I too am experiencing more heartburn symptoms especially at night and am taking tums or rolaids for this.
I was told its pretty normal. As your uterus grows it pushes everything else higher in your rib cage, which causes the pressure and your hearburn.
When my sister in law was pregnant she had pressure under her ribs from very early on, we were talking about this yesterday, she said it was painful too. She now has a 4 month old little boy! I haven't had this myself, I just remember from my previous pregnancies being kicked in the ribs a lot in the last trimester! But I do know all about heartburn!! I take gaviscon cool liquid- 20 mls every night before bed, it works wonders!